Let default_repo_config configure multiple repositories

[jorgemoralespou]

When configuring default_repo_config it can be necessary to add multiple repositories.
For this, we have defined default_repo_config as map [], and iterate in settings.xml.erb through the repositories to add them.
We can send you the modified code if you wish. It is straightforward.

We have modified:

• settings.pp
• settings.xml.erb

[carlossg]

could be interesting to see a pull request. Would like to keep it backwards compatible

[brettporter]

Addressed by #14