Updates .gitignore

To ignore swap files from getting into repository
currently the implemented ignore is *.swp
however vim adds more swap files if these files exists,
so improving this with *.sw?

Change-Id: Iff581457cabe936b8b285142caff92fcc849f04a
Closes-Bug: #1255876
use six.StringIO for compatibility with io.StringIO in python3

The newer version of six (1.4.1) provides six.StringIO which
is a fake file object for textual data. It's an alias for cStringIO.StringIO,
in python2 and io.StringIO in Python3.

Change-Id: If1ccfca128385f976938f0f0c74573687faad9ac
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Merge "Updates .gitignore"
Merge "use six.StringIO for compatibility with io.StringIO in python3"