Added help text for the debug option

This adds a short help text for --debug on the command line. Prior to
this short help text the debug option was hidden.

Change-Id: I2e641ec496e596fcc4879855ac750d957522be88
Closes-Bug: #1328813
Using six.u('') instead of u''

In a few places, there's some u'' strings, this patch replaces
them by six.u(''), as this fixes things when running the unit
tests in Debian Wheezy.

Change-Id: I60c01f85901a33a0e3e7a255049084126558f031
Merge "Added help text for the debug option"