Updates image upload directories to be number based.

resolves #2285

- Moves to using moment.format('MM') to use the date formatting of a month
- Moves storage modules to use prototypes and to create prototypes
that inherit from the base storage ctor.
- Creates utils.inherits for easy set-up of prototype chain.
Isn't this available in the [native util module](http://nodejs.org/docs/latest/api/util.html#util_util_inherits_constructor_superconstructor)?