display total number of pages and results in the meta section of an API call

Some Flask API frameworks, such as Flask-Restless, currently report total number of pages on each API call. In my projects, I sometimes find myself wanting this information readily available on each API call, in addition with the total number of available results. Especially when I build frontends that pulls data directly from my APIs.

This pull-requests extends the Meta field of all API calls with 'num_pages' and 'num_results', reporting total number of pages and total number of results available for that particular API call.

Tests are changed accordingly and all run successfully.

Documentation changed accordingly.