Fix Unicode search

The backend broke down on searches containing unicode characters as the
_is_ipv4 function tried to mangle the data through inet_aton which
failed miserably on Unicode and raised an exception which we did not
catch. We catch it now, so all is good.

Also removed some encode/decode mangling which is not needed in Python
2.7.3.

As far as I can tell, unicode searches now works on a recent Python
(2.7.3).

Fixes #247.
Bah, fix last commit

Accidentally removed a bit too much code :P
Add Travis-CI testing for Python 2.4 to 2.7
Merge branch 'unicode-search'
Pass extra_query to backend function

Fixes extra_query support for smart_search_vrf.

Slightly related of #292.
Add vrf_id arg to XHR smart_search_vrf

We can't pass a complete dict-SQL as an argument to the XHR from a
javscript, so instead vrf_id was added which builds the dict-SQL in the
XHR function and adds that as extra_query to the smart_search_vrf
function in the backend.

Part of #292
extra_query for smart_search_vrf in pynipap

Part of #292.
Fix default VRF in VRF selector in web UI

The default VRF / No VRF used to be a static entry in the VRF selector,
but since the name / description is now editable, we need to fetch it
from the backend. We use some extra parameter to smart_search_vrf to
accomplish that!

Part of #292
Back out change for default VRF

In the XHR class we still need to handle the case where the VRF might be
None since a pool without any prefixes associated with it will not have
an implied VRF.

Part of #292.
Fixed VRF selector menu for default VRF

The VRF selector now shows the default VRF per default as well as on
empty searches, just like the old one did. The difference is in that the
old way was to display static information while the new way is to do a
search towards the backend to get the default VRF information. We need
to do that as the name and description of the default VRF can be
changed.

Fixes #292.