Refactor `catalog' package.

 * Move connectors in a dedicated package.
 * Remove unused `GetValue' handling.
 * Clean up both package code.
 * Refactor of `graphite' connector code.
Change slices initialization syntax.
Add package doc for `catalog' and `connector'.
Rewrite and clean up `auth' package.
Rewrite and cleanup various packages.
Make `auth' handlers use interfaces.
Refactor server package.

 * Move main server code from `facette' command to `server' package.
 * Remove dependencies on Gorilla packages.
 * Add parse helpers.
 * Deduplicate code in catalog and library handlers.
 * Clean up code.
 * Temporarily remove web UI code.
Remove Gorilla packages from third-party folder.
Fix RRD connector metric DS name suffix.
Re-add administration panel in `server' package.
Add missing default route for server.
Update dependencies list in documentation.
Unexport URL paths in server package.
Re-add load wait mechanism in `server' package.
Merge 'master' of github.com:facette/facette

Conflicts:
	pkg/catalog/connector_graphite.go