Feat/more post routeswq

Added routes/logic/models for saving vets, vaccines, pet_vaccines.
Updated tests to include basic write functionality.
Built out framework for admin controllers to mirror user controllers.
Added put/delete requests for user-side routes
we should implement PUTS as a PATCH request, see "save" docs for bookshelf.js

If you only wish to update with the params passed to the save, you may pass a {patch: true} flag to the database:

// update authors set "bio" = 'Short user bio' where "id" = 1
new Author({id: 1, first_name: 'User'})
  .save({bio: 'Short user bio'}, {patch: true})
  .then(function(model) {
    // ...
  });