router: implement RelativeURLPath
* experimental boosting & name resolution
* adding fields to search
* updated schema
Merge pull request #177 from rogpeppe/076-relative-url

router: implement RelativeURLPath

We can use this for generating correct relative URLs in pages that
we serve (we'll use it initially in the generated SVGs for bundles).

Also add some copyright notices that were needed.
Merge pull request #180 from urosj/v4

CS Search: Experimental boosting & name resolution
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
Only index latest charm version.

Use elasticsearch versioning to make sure that only
the latest version of the charm or bundle is indexed.
Therefore only returning the latest version in search
results.