[GSoC'15] Integrate LO with GNOME - WR#6

[Pranav Kant]

The most important commit this week is the WIP push to make LOK call
(open_document) in a separate thread, along with other bugfixes.

This included adding two more signals to the widget viz. load-started,
load-finished to add support for asynchronously loading the document.
This would greatly enhance the responsiveness of the widget, and not
freeze the UI while loading any document.

In next few weeks, I would improve this and add more LOK calls in
separate threads.

-- 
Regards,
Pranav Kant
http://pranavk.me