Move Rosella submodule

Fixes #17
Minimal Repository and Index API
Add a C wrapper for some functions
Update NCI file
Add a Blob class
Update Oid class
Add commit parsing API
Add Config Parsing API

Also commit updated setup.winxed
Add a RevWalk class
Updated tests

Tests for all classes.
Fixes #10
Fixes #15
Fixes #16
Update git2.pir
Add wrapper functions pir