Adds Solr stats
Adds stats docs to Readme
Refactors stats code to be more in line with facets
Adds reference support for stats facets
Fixes syntax error on Ruby 1.8.7
Fixes another 1.8.7 syntax error
Fixes remaining 1.8.7 issues
Small change to trigger new travis build
Merge pull request #503 from fivedigit/stats

Adds Solr stats support