Allow automatic material property output from Output objects

This adds material property output to be enable from [Outputs] block, see http://mooseframework.org/wiki/MooseSystems/Materials/#output-via-outputs

This will allow for simple material output for problems that have many Material objects defined with the same property in each.

closes #3538
Did you mean to have this mix of C-style and C++-style comments?  If it's not Doxygen, I'd just pick one or the other.