* Some Solr configurations have complex queries
  defined in solrconfig.xml with custom parameters,
  because of this, you might not always want the
  'q' parameter sent, this patch allows you to set
  'query' to NULL so that when you do it prevents
  'q' from being sent at all.

- corrected the input format for the datetime objects (prefix timestamps with @)
- fixed timezone issue by forcing UTC
- refactored formatDate into a single function and without duplicate date objects

fix issue #58 add formatDate to query helper

- added both the original resource and the urldecoded version to the __toString() output
- added a testcase for __toString()