Merge github.com:allegro/ralph

Conflicts:
	src/ralph/discovery/plugins/openstack.py
Pin null module version
Merge pull request #492 from deshipu/master

Pin null module version
Make the version in footer link to the changelog
Merge github.com:allegro/ralph
Add xlwt to install_requires
Move changelog url to a constant
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.
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
Show splunk column in the ventures report
Merge pull request #497 from deshipu/master

Speed up the display of loadbalancers.
Merge pull request #498 from deshipu/splunk

Splunk column in the ventures report
User preference mechanism and custom user home page
Merge branch 'master' of git://github.com/allegro/ralph into user_preferences
i18n
PEP8