[#43] Simple geocoder for countries and US admin

The 'location_search' action provides an easy geocoder for countries, US
states, counties and postal codes, returning a bounding box in GeoJSON
for all the matching results.

The backend table used by the service can be found here:

https://dl.dropbox.com/u/3109637/locations.20130325.sql.zip
[#43] Map widget for drawing a spatial filter

On the filter section of the dataset search page there is a now a map
widget that allows users to define an area of interest to limit search
results, in the same way that the facets do.

The bbox and extent are passed as parameters so they can be reproduced
on the resulting page. The map is powered by Leaflet.
[#43] Autocomplete text field for the location API

In addition to the map widget on the dataset search page, an
autocomplete text field now returns results from the locations API, and
sets their extent to the map widget so it can be used as a spatial
filter.

When a result is selected, a message is published so the map widget can
load the geometry and rezoom. The location named is added to a hidden
field so it can be carried forward to next page.

The module is loosely based on the autocomplete.js module on CKAN core,
but highly modified because it was difficult to adapt the existing one
to different results.
[#43] Save previous location if present
[#43] Remove all params when clearing spatial filter

After okfn/ckan#705, h.remove_url_param accepts a list of all the
parameters to remove. We can then get rid of ext_bbox, ext_prev_extent
and ext_location in one go.
[#43] Small template and CSS tweaks to current spatial query implmentation
[#43] Blockblock update
[#43] Spatial search now expands on adding rectangle box
Merge branch 'master' into 43-spatial-search

Conflicts:
	ckanext/geodatagov/logic.py
	ckanext/geodatagov/plugins.py
resolve merge conflict
Merge branch 'master' into 43-spatial-search
Merge branch 'master' into 43-spatial-search
Merge branch '46-org-type' into 43-spatial-search

Conflicts:
	ckanext/geodatagov/fanstatic_library/styles/geodatagov.less
Merge branch '43-spatial-search' of github.com:okfn/ckanext-geodatagov into 43-spatial-search
Merge branch 'master' into 43-spatial-search
Merge branch 'master' into 43-spatial-search
Merge branch 'master' into 43-spatial-search
Merge branch '43-spatial-search' of github.com:okfn/ckanext-geodatagov into 43-spatial-search
Merge branch 'master' into 43-spatial-search
[#43] Fix location not being remembered on successive searches