[DNS] zone import should not truncate records ending in .

### Description
When running:
```az network dns zone import -f cshort.co.txt -n cshort.co --verbose```

The character before the trailing dot (.) is being truncated from BIND zone files. When @kris-nova removed the trailing dot it appeared to import as desired. Here is command's output:

```
az network dns zone import -f cshort.co.txt -n cshort.co --verbose
== BEGINNING ZONE IMPORT: cshort.co ==

(1/9) Imported 1 records of type 'cname' and name 'time.cshort.c'
(2/9) Imported 1 records of type 'cname' and name 'tmf.cshort.c'
(3/9) Imported 1 records of type 'cname' and name 'www.cshort.c'
(4/9) Imported 1 records of type 'cname' and name 'clock.cshort.c'
(5/9) Imported 1 records of type 'cname' and name 'ntp.cshort.c'
(6/9) Imported 1 records of type 'soa' and name '@'
(7/9) Imported 1 records of type 'a' and name 'cshort.c'
(9/9) Imported 2 records of type 'txt' and name 'cshort.c'

== 9/9 RECORDS IMPORTED SUCCESSFULLY: 'cshort.co' ==
```

Zone file can be found here: https://pastebin.com/WCY6bZZp
---

### Environment summary

**Install Method:** How did you install the CLI? (e.g. pip, interactive script, apt-get, Docker, MSI, nightly)
Answer here: interactive script

**CLI Version:** What version of the CLI and modules are installed? (Use `az --version`)
Answer here: ```az --version
azure-cli (2.0.14)

acr (2.0.10)
acs (2.0.13)
appservice (0.1.13)
batch (3.1.1)
billing (0.1.3)
cdn (0.0.6)
cloud (2.0.7)
cognitiveservices (0.1.6)
command-modules-nspkg (2.0.1)
component (2.0.7)
configure (2.0.10)
consumption (0.1.3)
container (0.1.8)
core (2.0.13)
cosmosdb (0.1.11)
dla (0.0.10)
dls (0.0.12)
eventgrid (0.1.2)
feedback (2.0.6)
find (0.2.6)
interactive (0.3.7)
iot (0.1.10)
keyvault (2.0.8)
lab (0.0.9)
monitor (0.0.8)
network (2.0.12)
nspkg (3.0.1)
profile (2.0.10)
rdbms (0.0.5)
redis (0.2.7)
resource (2.0.12)
role (2.0.10)
sf (1.0.6)
sql (2.0.9)
storage (2.0.12)
vm (2.0.12)

Python (Darwin) 2.7.13 (default, Apr 4 2017, 08:47:57)
[GCC 4.2.1 Compatible Apple LLVM 8.1.0 (clang-802.0.38)]

Python location '/usr/local/lib/azure-cli/bin/python'```

**OS Version:** What OS and version are you using?
Answer here: macOS 10.12.6

**Shell Type:** What shell are you using? (e.g. bash, cmd.exe, Bash on Windows)
Answer here: fish