NoTask - Added editorconfig and rubocop gem

## Changes 

### Editorconfig
* Added .editorconfig file, you can find more information here: http://editorconfig.org/

### Rubocop
* Added rubocop gem and updated code to conform to rubocop standards - please note however that I have not fixed all issues, please see the link below to view the configuration settings: 

https://github.com/jonathanchrisp/site_prism/blob/rubocop/.rubocop.yml 

These could be removed and the offending code fix as and when. To see more information about Rubocop please see: https://github.com/bbatsov/rubocop

* Please note that I added rubocop to the .travis.yml file, this runs before rake.

I've ensured that all units tests passed locally as expected. This appears to be a large change but the majority of the changes are small updates, such as removed "" in favour of '' etc.
Was this change made by Rubocop? It seems to be against the following rule from Ruby style guide:
> Prefer single-quoted strings when you don't need string interpolation or special symbols such as \t, \n, ', etc.
So IMHO double quotes should be considered good enough as special symbol `'` is used here.