Sets default page size to 100 documents

It used to take too long to load large corpora, specially when using the
browsable API, since the javascript processing necessary to pretty print the
json documents was too much for most browsers.

The default is 100, but the user can set the page size by sending 'page_size' as
a url parameter.
Merge pull request #103 from flavioamieiro/feature/pagination

Sets default page size to 100 documents
Allows users to authenticate using a token
Automatically creates Auth Tokens for new users
Fixes TestWithMongo

For some reason saving a string to gridfs no longer works, so we have to send a
file-like object.
Brings fix from f839d5b to the `reset_gridfs_collection` script
Creates a page with the user's API Token

This also includes a short explanation on how to use it to login.
Adds correct css class to the page title

@andrebco might like this commit
Merge pull request #104 from flavioamieiro/feature/token_auth

Allows users to authenticate using a Token