(PDB-238) - Remove v1 API

This commit removes the v1 API and starts toward separating the PuppetDB
HTTP API functions from the routes that lead to them. This commit contains:

- Moving v1 functions used by v2/v3 to api.clj
- Having v2/v3 call into api.clj from their routes
- Move former v1 tests into test/api.clj
- Remove all v1 namespaces and the namespaces calling them
- Changed the v1 tests to use the functions themselves (not going in through the top *app*)
- Add tests for the same api calls going through both v2 and v3 routes
- Remove v1 references in the docs