Upgrade to Solr 4.4.0

This makes the necessary requirements to upgrade to Solr 4.4.0.  A simple benchmark shows same performance before/after.  I'll post graphs tomorrow.

Solr 4.4.0 also enables us to try out the new "schemaless" mode but that should be it's own PR.  Furthermore, 4.5.0 should be coming out any day now.  That upgrade should be done for the 0.11.0 release.  But I wanted to update to 4.4.0 first to make that transition easier.