Merge pull request #493 from deshipu/master

Make the version in footer link to the changelog, add lxwt to install_requires, fix disk serial numbers for OCZ disks.
Speed up the display of loadbalancers.
Better select_related for load balancers
Merge github.com:allegro/ralph
Merge branch 'master' of github.com:deshipu/ralph

Conflicts:
	src/ralph/ui/views/common.py