Fix geventhttpclient version

Refs:
http://lists.opencontrail.org/pipermail/dev_lists.opencontrail.org/2014-April/000930.html
Use dsetia patch to handle server certificates validation

Remove pin of python-geventhttpclient.
Refs: LP https://bugs.launchpad.net/opencontrail/+bug/1306715
Refs: GH #31
Merge pull request #31 from sbadia/geventhttpclient

Fix geventhttpclient version