enhanced sitemaps, now a user can easily define the models used for the sitemap by defining DATA_SITEMAPS config key with a list of models
added a recompile stylesheets action to the administrator controller
made the stylesheet compilation process use the cache helper
added an administrator action for recompilation of stylesheets
enhanced searches similar to sitemaps, user can define which controllers are searchable.

The appropriate model must provide a search method.
removed a redundent header content-type call
bugfix for sitemaps cache