Feature/mg/library artist extention

- list all artists
- click on tile to search for the name of the artist
- for library and event song suggestions/votings
- responsible layout

![2014-12-28 16_39_05-songster - you make the party](https://cloud.githubusercontent.com/assets/1218033/5564223/88a09882-8eb0-11e4-93f1-b83f476f032d.png)
![2014-12-28 16_39_13-songster - you make the party](https://cloud.githubusercontent.com/assets/1218033/5564224/8aa956a0-8eb0-11e4-898d-fcab512f798f.png)
![2014-12-28 16_38_43-songster - you make the party](https://cloud.githubusercontent.com/assets/1218033/5564225/8cb457b0-8eb0-11e4-84ae-0ab962155e24.png)


you could add here that the eventid must be a valid ID
Because you have /event/.../artist it must exist somehow, so just checking that it is an ID is good
There are code snippets in other parts of the backend that check for this (search for .isMongoId())