[FR][Add] Adding auto-cleaning when prefix is used despite the WARNING in the help

Lots of action need to have clean <<TAG>> precision.

For example, when calling : twgit release remove 1.2.3, twgit is looking to remove release-1.2.3.
Some users may now call : twgit release remove release-1.2.3 without being blame for using release-.
We just show them message 'We assume tag was 1.2.3 instead of release-1.2.3'

Message could easily be updated in inc/common.inc.php if needed (btw, man should also update the UnitTest :D)