jlink transport plugin is broken on python 3

python 3:
```
12:30 $ iotile -vvvv hw --port jlink connect_direct device=nrf52 controller remote_bridge create_script add_setversion_action os 2059 -v '1.0' add_setuuid_action 0x01 send_script wait_script back
19-04-05 12:30:40.036 INF pylink.jlink Device "NRF52832_XXAA" selected.
19-04-05 12:30:40.039 INF pylink.jlink Found SW-DP with ID 0x2BA01477
19-04-05 12:30:40.048 INF pylink.jlink Found SW-DP with ID 0x2BA01477
19-04-05 12:30:40.053 INF pylink.jlink Scanning AP map to find all available APs
19-04-05 12:30:40.057 INF pylink.jlink AP[2]: Stopped AP scan as end of AP map has been reached
19-04-05 12:30:40.057 INF pylink.jlink AP[0]: AHB-AP (IDR: 0x24770011)
19-04-05 12:30:40.057 INF pylink.jlink AP[1]: JTAG-AP (IDR: 0x02880000)
19-04-05 12:30:40.057 INF pylink.jlink Iterating through AP map to find AHB-AP to use
19-04-05 12:30:40.062 INF pylink.jlink AP[0]: Core found
19-04-05 12:30:40.062 INF pylink.jlink AP[0]: AHB-AP ROM base: 0xE00FF000
19-04-05 12:30:40.065 INF pylink.jlink CPUID register: 0x410FC241. Implementer code: 0x41 (ARM)
19-04-05 12:30:40.065 INF pylink.jlink Found Cortex-M4 r0p1, Little endian.
19-04-05 12:30:40.171 INF pylink.jlink FPUnit: 6 code (BP) slots and 2 literal slots
19-04-05 12:30:40.183 INF pylink.jlink CoreSight components:
19-04-05 12:30:40.183 INF pylink.jlink ROMTbl[0] @ E00FF000
19-04-05 12:30:40.190 INF pylink.jlink ROMTbl[0][0]: E000E000, CID: B105E00D, PID: 000BB00C SCS-M7
19-04-05 12:30:40.195 INF pylink.jlink ROMTbl[0][1]: E0001000, CID: B105E00D, PID: 003BB002 DWT
19-04-05 12:30:40.200 INF pylink.jlink ROMTbl[0][2]: E0002000, CID: B105E00D, PID: 002BB003 FPB
19-04-05 12:30:40.205 INF pylink.jlink ROMTbl[0][3]: E0000000, CID: B105E00D, PID: 003BB001 ITM
19-04-05 12:30:40.212 INF pylink.jlink ROMTbl[0][4]: E0040000, CID: B105900D, PID: 000BB9A1 TPIU
19-04-05 12:30:40.217 INF pylink.jlink ROMTbl[0][5]: E0041000, CID: B105900D, PID: 000BB925 ETM
19-04-05 12:30:40.218 INF pylink.jlink Found SW-DP with ID 0x2BA01477
19-04-05 12:30:40.223 INF pylink.jlink Found SW-DP with ID 0x2BA01477
19-04-05 12:30:40.228 INF pylink.jlink AP map detection skipped. Manually configured AP map found.
19-04-05 12:30:40.228 INF pylink.jlink AP[0]: AHB-AP (IDR: Not set)
19-04-05 12:30:40.231 INF pylink.jlink AP[0]: Core found
19-04-05 12:30:40.231 INF pylink.jlink AP[0]: AHB-AP ROM base: 0xE00FF000
19-04-05 12:30:40.233 INF pylink.jlink CPUID register: 0x410FC241. Implementer code: 0x41 (ARM)
19-04-05 12:30:40.233 INF pylink.jlink Found Cortex-M4 r0p1, Little endian.
19-04-05 12:30:40.340 INF pylink.jlink FPUnit: 6 code (BP) slots and 2 literal slots
19-04-05 12:30:40.342 INF pylink.jlink CoreSight components:
19-04-05 12:30:40.343 INF pylink.jlink ROMTbl[0] @ E00FF000
19-04-05 12:30:40.344 INF pylink.jlink ROMTbl[0][0]: E000E000, CID: B105E00D, PID: 000BB00C SCS-M7
19-04-05 12:30:40.345 INF pylink.jlink ROMTbl[0][1]: E0001000, CID: B105E00D, PID: 003BB002 DWT
19-04-05 12:30:40.346 INF pylink.jlink ROMTbl[0][2]: E0002000, CID: B105E00D, PID: 002BB003 FPB
19-04-05 12:30:40.347 INF pylink.jlink ROMTbl[0][3]: E0000000, CID: B105E00D, PID: 003BB001 ITM
19-04-05 12:30:40.348 INF pylink.jlink ROMTbl[0][4]: E0040000, CID: B105900D, PID: 000BB9A1 TPIU
19-04-05 12:30:40.349 INF pylink.jlink ROMTbl[0][5]: E0041000, CID: B105900D, PID: 000BB925 ETM
19-04-05 12:30:40.368 CRI iotile_transport_jlink.jlink_background Starting JLink control thread
19-04-05 12:30:40.788 INF iotile_transport_jlink.jlink_background Found control stucture at address 0x20006BFC, word_length=17
Downloading script: [----------------------------------------] Estimating time left19-04-05 12:30:40.918 ERR iotile_transport_jlink.jlink_background Error executing command 7 with args (DeviceInfo(jlink_name='nRF52832_xxAA', ram_start=536870912, ram_size=65536, flash_start=0, flash_size=524288, rpc_trigger=RPCTriggerViaSWI(register=3758154240, bit=20)), , b'\xe1\xd7\x95\x00\xeb\xff\x87T\x90F(_\xc2h/3L=.\x1f>\x00\x00\x00\x16\x00\x00\x00\x04\x00\x00\x00\x0b\x10\x08\x08\x0b\x08\x00\x04\x0b\x08\x00\x04\x01\x00\x10\x00\x00\x00\x04\x00\x00\x00\x06 \x08\x08\x01\x00\x00\x00', .update_progress at 0x10eeb59d8>)
Traceback (most recent call last):
File "/Users/lukee/arch/env/py3/lib/python3.7/site-packages/iotile_transport_jlink/jlink_background.py", line 84, in run
result = func(*args)
File "/Users/lukee/arch/env/py3/lib/python3.7/site-packages/iotile_transport_jlink/jlink_background.py", line 149, in _send_script
for i in xrange(0, len(script), 20):
NameError: name 'xrange' is not defined
Downloading script: [########################################] Estimating time left
HardwareError: Error executing remote script
Additional Information:
error_code: 2147811349
19-04-05 12:30:40.929 INF iotile_transport_jlink.jlink_background stop command received
19-04-05 12:30:40.929 CRI iotile_transport_jlink.jlink_background Shutting down JLink control thread
```