Fix for issue #9.
Fix for issue #9.

The geos_config `--cflags` was returning a `-I /usr/...` which was being
appended to a `-I` in `CPPPATH_GEOS`. So using `--includes` now.

kashif/node-geos,kashif/node-geos,kashif/node-geos,diorahman/node-geos,diorahman/node-geos