feat(auth): migrate Application model from MongoDB to MySQL

- Add Sequelize migration creating the 'application' table
- Add Application Sequelize model with slugify, toJSONFor, toAuthJSON
- Rewrite passport-headerapikey strategy to use DB.Application
- Rewrite applications.routes.js to use Sequelize (findAll, count,
  build/save, destroy) instead of Mongoose
- Fix pre-existing bug: passport was querying { encryptedKey } but the
  stored field is named 'apikey'
- Add Application to MySQL models index and relationships
- Remove Application from Mongoose models index and delete the schema

src/config/passport-headerapikey.js

@@ -2,9 +2,7 @@ var secret = require('.').secret,
     bcrypt = require('bcrypt');
 const passport = require('passport');
 var HeaderAPIKeyStrategy = require('passport-headerapikey').HeaderAPIKeyStrategy;
-var mongoose = require('mongoose');
-var Application = mongoose.model('Application');
-
+const DB = require('../database/mysql');
 
 passport.use('headerapikey', new HeaderAPIKeyStrategy(
     { header: 'Authorization', prefix: `${process.env.AUTHORIZATION_PREFIX} ` },
@@ -12,13 +10,13 @@ passport.use('headerapikey', new HeaderAPIKeyStrategy(
     function (apikey, done) {
         const salt = secret;
         Promise.resolve(bcrypt.hash(apikey, salt)).then(function (encryptedKey) {
-            Application.findOne({ encryptedKey: encryptedKey })
+            DB.Application.findOne({ where: { apikey: encryptedKey } })
                 .then(function (application) {
                     if (!application) {
-                        return done({message: "Application can't be found.", status: 404}, false, false);
+                        return done({ message: "Application can't be found.", status: 404 }, false, false);
                     }
                     return done(null, application);
-            });
+                });
         }).catch(done);
     }
 ));