Create boilerplate css code for navigation utilities, like delete and edit

Motivation for this is to ease the pain of creating and standardize often used actions for navigation entries, like editing the entry or deleting it. It allows to keep and evolve mobile styles in core.

Example:
![utils](https://cloud.githubusercontent.com/assets/195053/4048676/fdbebf9e-2d45-11e4-884a-0bfb1d7e5553.png)

How it works is documented here: https://github.com/owncloud/documentation/pull/501

**TODO**:
* [x] Proper paddings for the ellipsis
* [x] Provide styling for inputs if you want to edit an entry
* [x] Create developer documentation 

@jancborchardt @MorrisJobke @georgehrke @DeepDiver1975 @LEDfan @raghunayyar