[READY] Implement tags overview

![screen shot 2014-08-27 at 16 06 39](https://cloud.githubusercontent.com/assets/642544/4060879/7f4d9ba4-2df3-11e4-92ed-adb32dd9dfed.png)

In this overview you can see the hours spent on a certain tag. You see the hours on that tag per user and per project. Also all the entries for that tag are listed, your entries in there can be edited. All the tags in the application are clickable now.

I also renamed the javascript charts file from project to charts since the charts are used in multiple places. I also moved some css to application because it was used in more places. Last of all i updated the annotation.
I think we have some duplication in the methods that generate these charts, we should look into pulling them out into a module that we could mix in or even an object that handles this, I did something similar to that in my open PR for entries timelines