Add META SUMMARY etc. to app market

[paulproteus]

Rationale:

• It would be super nice to feature every app from it's capnp short description + logo.
• Context of request: @synchrone (an app author), at http://logbot.g0v.tw/channel/sandstorm/2016-02-25#136

Details:

• Maybe we can start doing server-side rendering of the app pages.

[paulproteus]

See also opengraph metadata, e.g. https://blog.kissmetrics.com/open-graph-meta-tags/

[zarvox]

FlowRouter has support for server-side-rendering, but only if you're using ReactLayout: https://github.com/kadirahq/flow-router/tree/ssr

We'd probably also have to do something about the fact that the app market server doesn't actually have a copy of the app index data to work with, which means it can't really render anything useful. So there'd be some work to integrate fetching (and caching?) the appropriate app index data serverside.

[kentonv]

In retrospect, perhaps doing the app market as a Meteor app (rather than static content) was a mistake.

[paulproteus]

Yeah - I think for this project, if we had gotten the feature set we had hoped for, then dynamic would have been essential. We do still have the ratings, though. But anyway.