Merge pull request #98 from sbesson/debug_log

Extend level size in logger format to properly display DEBUG logs
Reorganize `scc rebase -h` options order
Refactor TestRebase to run tests as part of the Travis build
Merge remote-tracking branch 'origin/master' into rebase_continue
Drop check for PR mergeability in `scc rebase` post PR opening

This commit closes #63. Adding some logic to handle the race condition seems
like a lot of investement for little benefit at this point.
Add failing test for bad object exception in `scc rebase`
Handle bad objects in `scc rebase`
Fix object existence check logic using `git cat-file -e <object>`
merge master -D org -I include -E exclude: PR 100 (Rebase improvements)