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
add: json backend to store user preferences

- json files are stored in userdata/
- sessions are now used, to keep the language preference
  - sessions are file-based and stored in sessiondata/, this can be
    easily changed
- userprefs.py manages the json files and provides methods to get
  the preferences and update them
add: rest interface for user preferences
add: unittests for user preferences
userprefs: replace  theme hook by context preprocessor
remove session_file_path

If not provided, Django will generate at tmp one for us.
Oh and Travis seems not to like it.
Top navigation alerts are back to white

In a previous synchronization effort they were
made grey, but they are white on purpose so they
are more noticable by the user.
update message for saved preferences
update: default location fot user data
woops, untabify
Adding style for disabled objects in objectbrowser.
Added dis-object class to object browser elements with register=0
rename: s/userprefs/userdata

and refactor userdata.User.__init__, to accept a Request as an
argument, instead of username.
woops, debugging code should not be here
update: userdata" parameters passed between methods for the Request
Removed changes that were going one step too far