First attempt to constrain slider position

This patch contains the first attempt to constrain the main library window slider position relatively to the window itself. It's still not working, thought.
Added support for Travis CI

Added the file required to activate support for Travis CI.
Added initial support for Parse Cloud Services

This patch adds initial support for Parse Cloud Services to eBookShelf
Another try to fix slider into status area

This patch changes some properties of the main window controller xib,
in an attempt to fix the slider size control to the status bar
constrains.