Build api

Hi, 

I was working a bit more in the library. Here is the list of improvements:

 - Unit test coverage 70% of files, 20% lines, still need a lot of unit testing in API Class and then we can refact because there are a lot of duplicated lines.
 - Created ObjectTwitterAbstract to extend the funcionality to transform in json, string and array the Twitter objects
 - Some objects were expecting params and others an array with data. Now all are expecting arrays
 - Fixed params that were not existing and some syntax errors.

Sorry for the big commit, but the library still have a lot of work to do...

Thanks!