Add support for Git

[sterlp]

https://github.com/sterlp/eclipse-peon-ai/tree/git-support

Idea:

1. extend Project info if git is supported
2. Add read git history
3. add read git commit
4. add diff file with main
5. add commit
6. add add file to commit
7. add remove file to commit
8. add show state -- dirty files
9. add list tags
10. add create diff between version

or is the CMD line easier than using eclipse egit and jgit?