Use different requirements list on Python 2 and 3

In Python 3 websocker-client not required (and previously requiested
version doesn't work at all).
Merge pull request #178 from rutsky/disable-websocker-on-py3

Use different requirements list on Python 2 and 3 (fixes #174)
Fix API version comparison
remove reference to uninitialized variable and extra parameter in function call
Merge pull request #181 from dangra/strict-version

Fix API version comparison for 1.10
Ensure that stream=True is passed to requests when version >= 1.8
Use requests to read chunk data instead of parsing the raw stream

The previous code had a bug in which it assumed that the chunk data had
no newlines in it.  In 0.9.0 newlines were added to the stream results,
which exposed this bug.
Merge pull request #184 from ibuildthecloud/fix-chunking

Use Requests.iter_lines to fix #176
parse_repository_tag function and accompanying test
make flake happy