[WIP] let users enter a description with hashtags when entering time

this is based #17 for linking to the tags overview from the description.

Still needs:
- [ ] autocompletion for tags
- [ ] mobile compatibility (text currently overflows)

![screen shot 2014-09-02 at 12 16 43](https://cloud.githubusercontent.com/assets/749864/4118207/fcaf7a28-329d-11e4-88c1-5577e6025fb4.png)
![screen shot 2014-09-02 at 12 53 45](https://cloud.githubusercontent.com/assets/749864/4118208/fcb735e2-329d-11e4-947b-e8f8d6668076.png)

@sn3p I'm sure there's a better way to do this? :dancer: