Restructured gui to accommodate future functionality.

* introduced info area where permanent information such as balance,
  order lag etc. can be displayed
* rearranged gui elements to gain screen estate
* introduced tabs to accommodate future features such as user orders
  and automated trading
Modified ui
Merge branch 'master' of git://github.com/sebastianhaberey/goxgui

Conflicts:
	goxgui/ui/main_window.ui
	goxgui/ui/main_window_.py
	goxgui/view.py