Support maven repository setting

[disacrol]

Users may want to change the default maven repository and manually set a different one in File | Settings | Build, Execution, Deployment | Build Tools | Maven | Local repository.

For example, if for corporate reasons it is advised to locate all downloaded artifacts in a location other than the default (~/ .m2).

[nailujx86]

An user should have the ability to override this setting across multiple repositories. The default maven repository might have a different absolute path for different users though.
Maybe user level global overrides in a folder like ~/.idea/autoconfig could help with this.