Better date picker

- Use local state for datetimepicker component (stops the picker from lagging when there are lots of sensors in the cursor and each click on the picker updates the cursor)

- Add +/- 1d +/- 1w buttons (cursor changes to pointer and text is highlighted on hover)
- Fixes bug in new profile page, where uuid for new profile wasn't a stringified uuid but a function to create a uuid

Fixes #408 
Fixes #216 

![image](https://cloud.githubusercontent.com/assets/2522010/4810216/864d8646-5eb1-11e4-8c5e-11f7dea5c78e.png)

Also a side fix for #438