Allow ngrams in URL text.

This sorts out a number of search issues:
 * ngrams match in URLs
 * Bundle Tags are supported in search
 * Support for charms and bundles with revision 0
Merge pull request #182 from mhilton/search-url-ngrams

Allow ngrams in URL text.

This sorts out a number of search issues:
 * ngrams match in URLs
 * Bundle Tags are supported in search
 * Support for charms and bundles with revision 0