Convert requests.ConnectionError to ClientException

Fixes bug 1163678

Change-Id: I16201eda29a56e3c1e6008989260425ddc124ea6
modify mistake in comment

init should be v3.0 rather than 2.0 in keystoneclient/v3/client.py

Change-Id: I54bcbaed38edcc9c0fb0a0138c1ee38492fd933d
Merge "Convert requests.ConnectionError to ClientException"