Added support for Resource Properties

This provides support for:
 - [DeletionPolicy](http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-deletionpolicy.html)
 - [DependsOn](http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html)
 - [MetaData](http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-metadata.html)
 - [UpdatePolicy](http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-updatepolicy.html)

In addition it address issue: seandst/cfn-pyplates#4
Brought in changes from PR#12

- Added minor tweaks to documentation
- fixes #4
setup.py reads licence from LICENCE file

- fixes #11
JSONableDict.add returns the added child

- fixes #5
Version bump: 0.2.0

Changes:
- Resource attributes (UpdatePolicy, MetaData, etc) now supported
- .add(child) methods return the added child to support dynamic creation
  of the child when .add is called, e.g.: `cft.resources.add(Resource())`