status.utils - Basic support for pynag MultiSite

This patch changes status.utils.livestatus() to use
the new pynag.Parsers.MultiSite() class.

There is still a lot of things to do. But this patch is a good start.

Parsers.MultiSite maintains backwards compatibility with old mk_livestatus
class so that most views in Adagios should still work.

What is left:
* Go through each view, and make sure that all calls to specific
  nagios object have the backend="something" so when a user clicks a
  service is definately loaded from the correct backend (in case of naming conflicts)

* Make a settings dialog for this (currently it is assumed that livestatus_path in adagios.conf
  is a seperated list, this is not ideal and might not be the case in the future.
context_processors - Fix error messages

Hide errors about missing destination_dir if there
is no nagios.cfg, its meaningless at that point.
status.utils workaround

Makes adagios default to a local livestatus connection
if none was configured
/status/detail - Support specifying a backend
servicelist snippet updated to support multisite
Merge branch 'master' into feature-multisite
New user preference: refresh_rate
adagios js, indent fixes
userdata.py - fix typo in error messages
userpref refresh_rate: support turning of reload

Now it is possible to put in 0 in refresh_rate to
signal adagios that no auto refresh is needed
Default user preference now based on global values

Change settings.PREFS_DEFAULT so that the default
values originate from settings.py. Which makes them
globally editable by changing adagios.conf
settings.py - remove duplicate TOPMENU_*
pep8 cleanup in settings.py
deprecate settings.THEMES_AVAILABLE

Instead use utils.get_available_themes()

Also, user preferences can now be changed globally
in AdagiosSettingsForm
Merge branch 'feature-multisite'