Development v2.0 branch

[amercader]

Main changes so far:

• Remove PostGIS requirement (#195). Still available if using ckan.spatial.use_postgis=true, but will be dropped in the future
• Refactor IPackageController hooks
• Updated and simplified bbox-based and spatial field based searches, cleaning up and consolidating code, extending test coverage
• Allow to customize the actual Solr spatial query
• Updated docs! https://docs.ckan.org/projects/ckanext-spatial/en/dev-v2.0/index.html
• Document and test custom indexing support and multiple geometries per dataset

[amercader]

For the record, I tried to use the RptWithGeometrySpatialField field type for the solr-spatial-field backend but queries were failing with the following error returned by Solr:

java.lang.AbstractMethodError: Receiver class org.locationtech.spatial4j.io.jts.JtsBinaryCodec$1 does not define or inherit an implementation of the resolved method 'abstract int read(byte[])' of interface org.locationtech.jts.io.InStream.

Strangely the index size didn't seem to change from the standard RPT field even though according to the docs it should store some form of geometry information. Anyway, documentation is extremely thin so I think we'll use the standard RPT field as default for now.