Patches to solr parameters and paths

Jason,

So, I had to tweak a few things in order to get this work work for me... don't know if you'll want to merge the changes or not.

1) base_solr_parameters should use :q instead of :fq

I'm not sure if this was just a typo or if you're trying to do something cooler with your solr query, but I had to change base_solr_parameters to use :q instead of :fq.  

2) adding get_solr_path method to determine the solr path if absent
from CatalogController

This is to address that comment I made earlier.  You could either have folks add the solr_path config variable to their CatalogController or use this method to get the path from config/solr.yml if it's that is absent.  Up to you...

let me know what you think...

...adam