Base Role from Object instead of ParseResource

This gives us everything we need from Object and
reduces code duplication

Add the ability to drop whole classes

implments #100

User.current_user() when a valid session token is provided

Add config object

Enable Session Tokens to be used to access ACL-protected objects.

Solve Datetime object not JSON serializable

ACL patch

Added Installation channel subscription modification

Handle adding and removing relations by User.

Added Installation channel modification so that account holders can manually add/remove subscriptions of users on their application

Simple fix using "default=" argument of json.dumps to pass a date_handler.

Update README.mkd with Role and ACL documentation.

Handle adding and removing relations from Roles.

This adds addRelation and removeRelation capabilities to Role, making it possible to add users to the users column and roles to the roles column in a Role object, for example. This prevents the error of Role not having the attribute addRelation or removeRelation when trying to add users or roles to a Role, which is critical for Role functionality.

Update datatypes.py to handle dict on properties

As a dict's iterator returns keys, sending {"key" : "value"} resulted in receiving ["key"] on dashboard
Uses dict.iteritems() instead

add file support

Reverting 2fde6572 to fix #67 (lazy loading fails)

Added role and ACL support

Improve error messages.

Subclassing User object