Add support for Synonyms lists

Here's a patch I wrote, which basically puts a drupal front end to the synonyms text file that solr uses.

Thanks for the patch!

I don't think we will commit this as is though. Since the format is so simple anyway, an interface doesn't seem worth it, and would just take up space. Plus, it's not uncommon to be running Solr on boxes other than Drupal. Would be interesting to see if Solr itself has a webservice for doing this.

If one of my co-maintainers objects, please let me know.

Best,
Jacob