ccm start get stuck

Hi,

Thanks for ccm, that's a great tool!
Lately I got an issue where it get stuck when I call ccm start against DSE (regardless of the cluster selected).
When I stop the process it provides the following:
```shell
root@MarcUbuntu16:~# ccm start
^CTraceback (most recent call last):
File "/usr/local/bin/ccm", line 90, in
cmd.run()
File "/usr/local/lib/python2.7/dist-packages/ccmlib/cmds/cluster_cmds.py", line 594, in run
allow_root=self.options.allow_root) is None:
File "/usr/local/lib/python2.7/dist-packages/ccmlib/dse_cluster.py", line 71, in start
started = super(DseCluster, self).start(no_wait, verbose, wait_for_binary_proto, wait_other_notice, jvm_args, profile_options, quiet_start=quiet_start, allow_root=allow_root)
File "/usr/local/lib/python2.7/dist-packages/ccmlib/cluster.py", line 409, in start
node.watch_log_for(start_message, timeout=60, process=p, verbose=verbose, from_mark=mark)
File "/usr/local/lib/python2.7/dist-packages/ccmlib/node.py", line 434, in watch_log_for
time.sleep(.5)
KeyboardInterrupt
```
Nothing get written in cassandra logs.
Many thanks for the help.

### Python version
2.7.12