[Git] Added git package

* Implemented branches module
* Implemented tags module
[Git] Improved naming

* Renamed function names in branches and tags
[Git] Implemented staging module
[Git] Fixed indentation and git calls

* Converted tabs to spaces
* Exchanged call with check_output
[Git] Added history module
[IO] Added io package

* Implemented files module
[IO] Removed type and engine arguments
Merge pull request #4 from frmwrk123/feature/1

Resolves #1