setup the database config file with sequelize

[amusameh]

This relates to issue #6 Here we setup the sequelize connection with the database which requires installing the(pg and pg-hstore) modules to help to establish the connection with the Postgres Db.

• Import the sequelize and env2 modules.
• Setting up the connection with the local Postgres database.
• create the models object and adding the Sequlize module and sequelize instance to it.
• export the models object.
• sync with the database using sync() method in the server/index.js file