Added support to extract mp4 videos from Movies folder
Saving videos on database

The previous commit doesn't save the videos on database, now they are.

We too have changed some methods to work with the MultimediaContent class, a
superclass for, eg., Audio and Video, instead its subclasses.
Extract similar commands in sync_video and sync_audio methods to a new method in Manager class
 Please enter the commit message for your changes. Lines starting
Merge pull request #2 from adorilson/fix-video

Fix video
Merge pull request #4 from adorilson/development

Development