Split out definition of routes on an express app into routes/index.js.

This will make it a lot easier to test out the actual routes and
their integration, rather than individual middleware or endpoints.
Removed hash, assertion from BadgeInstance schema. Assertion endpoint works.

However, the badge URL doesn't yet work, so the new routes test suite I
added currently skips b/c I want to fix the badge URL and then add to the
test.
Got /badge/meta/:shortname and test working.

Now need to make sure its issuer and criteria URLs are valid.
Added /program/meta/:programId endpoint and test.

Also a criteria endpoint test.
Refactored tests/routes.test.js to make it easier to read.

This, and its previous commits, resolves #147.