Implementing last changes for multi git and git submodules

Hello,

Currently the plugin supports single git/svn repository.
There is an issue regarding the support for multiple git repositories here #42

I would like to contribute towards making that feature in the plugin. I am thinking of doing it in some of the following ways:
1. In each multi-git setup, provide the configuration parameters for each repository
2. Provide a configuration file in the project, the revision parameters for each repository, OR
3. Provide a configuration file with revision parameters in each repository in multi-git and submodules.

We use both multi-git and submodules in our jenkins configuration. I would like to contribute towards extending the functionality for them as well.

Any feedback will be appreciated.