kibana: Reduce cache duration for metadata

Caching the metadata for 15 minutes causes frontend devices to wait to
see the new index when the UTC date rolls over. Reducing the cache
duration should make this lag less noticeable while still providing some
value for clients that are refreshing at a high rate.

Change also includes the addition of the .*/_aliases proxy mapping
needed by the latest versions of kibana.

Change-Id: I07dc6a20ebf4f966db4d9867e5ff8b60fdfc3cfd