ENH: adding convenience function run_ica

Adding run_ica to mne.preprocessing, a custom function implementing an automated artifact removal workflow. Tests run fine, the terminal print out looks nice to me. From my side ready for review. To keep things simple I decided to first only support raw data.
For details also see discussion in #364. 

--- oddly some of the recently added changes appear here in my branch. They should not differ from master. Might this be related to #359 ? Any ideas, what to do with it?