Excel Functionality

 - [x] Full Keyboard Navigation
 - [x] Editor Functionality
   - [x] Simple Text Editor
   - [x] Drop Down Editor
   - [x] Checkbox Editor
   - [x] Autocomplete Editor
   - [x] Datepicker Editor
   - [x] Custom Validation
 - [x] Copy Cells
 - [x] Paste Into Cells
 - [x] Dragdown functionality

 - [x] Increase scrolling speed when > 3 columns
 Scrolling with anymore than 3 cells was ridiculously sluggish. React Perf is awesome!!
#### Went from this 
![react sgrid low](https://cloud.githubusercontent.com/assets/1432798/4043762/e6ffda7e-2d16-11e4-97f6-706fea34b4b0.PNG)

#### To this
![image](https://cloud.githubusercontent.com/assets/1432798/4043770/12416e50-2d17-11e4-9d8a-7d0414322819.png)