add a bunch of files to .gitignore.
Modify the specs slightly to run on JRuby and use pg_config

use pg_config to determine postgresql bin directory and use it if
available. Also, if we're running on a no fork system redirect the
output of the commands.  Otherwise pg_ctl won't leave the shell process
group and block the specs from finishing
generate the errors file if it's missing
Add support for JRuby