Sc/create location

Changelog
=========
* Create Location model  ```location.rb``` and migration  ```20140429183646_create_locations.rb```  
*  Create spec  files. ```locations.rb``` and  ```location_spec.rb``` 
* Create  ```location.rb``` in ActiveAdmin
* Add task  for create a Location  ```populate_locations.rake```   
* Add csv files for Add cities and  states   ```arg_cities.csv```  ```arg_states.csv``` 
* Add populate_location rake in  ```seed.rb```