Turn on browser caching to ease serving of /browse

[ksclarke]

Problem:

Client-side caching isn't turned on on the Vert.x HTTP responses by default. Turning it on would help the performance of the site. See Jiiify for how to turn it on... e.g.

response.putHeader(Metadata.CACHE_CONTROL, Metadata.DEFAULT_CACHE_CONTROL);

Acceptance:

• When looking at the response headers of a GET request to /browse we see caching turned on