Namespacing

[gnikyt]

Adds ability to namespace apps.

Changes:

1. Added namespace column to shop table
2. Global scope to Shop model which appends where namespace = ? to all queries
3. An observer to automatically add namespace to a new shop on create
4. New config entry to define namespace either via config PHP file for env

Tests pass, physical tests seem fine. Reviewing.

[coveralls]

Coverage remained the same at 100.0% when pulling 0b4e62a on namespacing into bc2c0c9 on master.