[#15] Reenable the Solr backend

It can be used against CKAN 2.0.1
[#15] Check CKAN version when using the Solr Search backend
[#22] No need to add `resource_proxy_enabled` to config
[#22] More details about resource_proxy
[#21] Add basic GeoJSON preview and fix set up of wms preview
[#21] Add properties information to popup, lighter style
[#21] Add GeoJSON preview docs
[#21] show object in popup, fix layout
[#21] Fix i18n calls

All the 'self' on the 'showError' function should be 'this', otherwise you
will refer to the window. Also 'this.i18n' assumes an 'i18n' key in the
module options. Looks like you are trying to pass some variables to the
string template, note the sprintf-like syntax.
[#21] Make popup table match the rest of CKAN tables
[#21] Add geojson previewer to index
Merge branch 'stable' of github.com:okfn/ckanext-spatial into stable