update docs url
updated postgres, postgis, gdal, geos, v8, plv8 to latest versions
fixed the install_name_tool command to change the dylib rpath for plv8
Download, build and install json-c
fixed jasper download path and libgeos file name.
updated v8 to 3.18.2
Merge pull request #103 from spacialdb/pg92

Updated Postgres.app to latest version