Explore

- adds explore pages per module type (e.g. mvc frameworks, testing)
- adds cascading grid layout to the index page 
- adds plugin to store certain data in explore.db (leveldb) and refreshes that each 6 hours. 
- all data layer interactions now go through a singleton instance which holds the dynamis, redis and couchdb clients. This ensures both the explore plugin and packages-pagelet will use the same clients

**Missing actual data, e.g. we have to tell explore what types and modules to use**
You can also set the `valueEncoding` of leveldb to `json`, that might be bit cleaner here.