Issue #222: formal API support
* catch api/* urls
* api/v1/foo/bar/ urls are parsed as an API call containing parameters
* new Transvision\API class to manage API request. 4 API services:
    - tm: Translation memory
    - search: Search on repositories (equivalent to current JSON API)
    - locales: return the list of locales for a getRepository
    - entity: Return all translations for an entiry (equivalent to onestring JSON API)
* new Transvision\Project class to make key data available everywhere without using globals
    - Project::getRepositoryLocales()
* Updated Transvision\Strings class with these methods:
    - Strings::Levenshtein() -> levenshtein distance working with Unicode strings
    - Strings::levenshteinQuality() -> quality index  based on Levenshtein algorithm
* Entiry service returns an empty json array for invalid entities + filters out {ok} strings for mozilla.org
* Refactor all search views to be MVC and separate data generation from presentation (needed to redirect JSON API calls to new API)
* All searches for strings and entities using the old json API are redirected to the new API, searches for 'strings and entities' on the old API are no longe supported