Add Expose plugin demo.

[dereuromark]

http://sandbox.local/sandbox/expose-examples

https://github.com/dereuromark/cakephp-expose

TODOS for plugin:

• [x] Add init_exposed_field PluginName.ModelName command to easily populate the uuid column for existing records per model/table.
• [x] Secure pagination (maybe using component and sane default blacklisting?) => for now manually through docs.
• [x] Add migration bake help for both new and existing table records
• [x] Finalize name: Expose, Exposed, ...?
• [x] Release 0.1