Explain groups for DeprecatedOpts

The patch extends the documentation for `DeprecatedOpt` and explains
that group==None means the deprecated name will be looked up in the same
group.

Change-Id: I54ba414d6a6862e1b00dfbf589563ef9f4df5cf3
warn against sorting requirements

Change-Id: I64ae9191863564e278a35d42ec9cd743a233028e
Addresses-Bug: #1365061
Work toward Python 3.4 support and testing

Change-Id: Iadb1b695b8314d385716619561a1604a41f6c8d5
Updated from global requirements

Change-Id: Id105ee1d495144517a684edd49116cba24060529
Merge "Work toward Python 3.4 support and testing"
Merge "Explain groups for DeprecatedOpts"
Looks for variable subtitution in the same group

When we do a variable subtitution we must try to look if the option
is avialable into the same group and then into the default one for backward
compatibilty.

Otherwise variable subtitution doesn't works when we change the group of
an option and deprecated the DEFAULT group.

Change-Id: Ie5750ee028a58fba6da225a8c4b4221e23db829f
Closes-bug: #1367790
Merge "warn against sorting requirements"
Merge "Looks for variable subtitution in the same group"