InfluxDB annotation support

This merge request add capability to create annotation in dashboard using **InfluxDB**. 

![screen shot 2014-07-13 at 19 05 26](https://cloud.githubusercontent.com/assets/43941/3565234/6107abb4-0ab0-11e4-85c2-679fb720cc4b.png)

We can create annotation using a query (or continuous query) in InfluxDB. Annotation have a query and a descriptive message.

![screen shot 2014-07-13 at 19 05 21](https://cloud.githubusercontent.com/assets/43941/3565235/65f15ef4-0ab0-11e4-8776-a5edbaf47284.png)

Message are visibile in result.

![screen shot 2014-07-13 at 19 05 42](https://cloud.githubusercontent.com/assets/43941/3565237/6bbee5e0-0ab0-11e4-8bc9-be2f626b3048.png)

This MR operate also a small refactoring to improve JS quality (coding standard, syntax, ...).