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
Manual merge with branch pg93, includes new build system from commit 9c6a12ae8de2a83fd0e109ff17945388a9bec621.
Bundled libtiff (see #111 and jasiek@85689c2d44a7954c44664e4bc2ebf4a93721320f)
changing .gitignore to accomodate new build workflow
- added missing makefile
- update project settings, should compile again
Merge remote-tracking branch 'origin/pg92'

The major change introduced in this merge is that I switched to a make
based build system. To change the postgresql build process, change the
makefile in src/makefile in the future. Hopefully git wil have an
easier time tracking changes in the makefile than tracking changes in
XCode project files...