Added convenience functions

To check if a string starts or ends with some string
Added an utility class to get content from the web

Based on curl. For now it gets JSON data from an URL.
Updated Mongo basic model and added File model

The Mongo basic model now understands how to deal with text searches and
sorting on such metadata (such as the relevancy score).

Added a File model for GridFS collections, to store files, including
their metadata.

Also added a .gitignore file. Totally forgot about this one.