Edge Values, aggregators, AJAX retries (and notifications), customizable link distance for editor

- Added edge values 
- Added aggregators (visible on the top right corner of the editor)
- Added AJAX retries (and graceful notifications upon failure)
- Made it possible to customize link distance using a slider (increases distance b/w nodes for slightly better visualization)
- Added the tabular view in the core editor API. (not end-end). 
 
![screenshot from 2014-05-22 02 17 39](https://cloud.githubusercontent.com/assets/514557/3051830/1ba23e78-e192-11e3-8653-f88e914e376c.png)
![screenshot from 2014-05-22 02 17 19](https://cloud.githubusercontent.com/assets/514557/3051831/1ba46a36-e192-11e3-8d65-9e4e38fba5bc.png)