Specify full namespace for Mysql2Adapter

Fix for 8d0016e. This probably worked in some cases because of weird
magic Rails does to constant lookup [1].

[1] http://urbanautomaton.com/blog/2013/08/27/rails-autoloading-hell/
Merge pull request #303 from jgonera/mysql-deletion

Specify full namespace for Mysql2Adapter
changelog for #303
Corrected the way to connect to the MongoDB using mongoid.
Fixed cucumber features, so Travis should now run both rspec and cucumber.
Removed unnecessary spaces.
Cucumber feature works without this, which is suspicious.