Add twgit feature status [<featurename>]

[geoffroy-aubry]

that display:
– the full name of the feature if connector Redmine or Github setted
– same indications as thoses displayed at the end of "twgit feature start":
Already on 'feature-4568'
(i) Local branch 'feature-4568' up-to-date with remote 'origin/feature-4568'.
/!\ Tags not merged into this branch: at least '1.1.2' to 'v1.3.0'. If need be: git merge --no-ff v1.3.0