remove 'init-branch' command

Use 'branch --init' instead...
Remove warning messages
Update release note
Update doc
Merge pull request #393 from pmiossec/remove_init_branch

Remove deprecated 'init-branch' command
Use libGit2Sharp to merge branches
throw an exception if commit not found
Update release note
Merge pull request #601 from pmiossec/libgit2sharp_merge

Use Libgit2sharp for merges
Refactoring...
Merge pull request #604 from pmiossec/refactoring_rcheckin

Refactoring and cleaning rchecking...
Expose TryParseChangesetId for testability
Failing tests for changeset id parsing
Fix changeset id parsing regex
Fix work-item option ( -w1234 is now supported)

to work how the help say...
Before this fix, only `-w1234:` or `-w1234:associate` was supported

Should fix #612
Merge pull request #613 from pmiossec/fix_workitem_option

Fix work-item option ( -w1234 is now supported)
Update xunit.runners also
Manage other strange cases
Merge pull request #617 from pmiossec/fix_find_commit_by_changesetid

Fix changeset id parsing to handle carriage returns (fix regression)