Added basic CRUD entity.

* I used Entity API and the model from http://www.trellon.com/content/blog/creating-own-entities-entity-api to build this custom entity
* I took the liberty of renaming the module from ckeditor_comments to ckeditor_comment
* since entities have bundles, we can also have different types of ckeditor_comments; they can be administered here: http://localhost/admin/structure/ckeditor_comment-types
* the comments can be administered here: http://localhost/ckeditor_comment which is this view: http://localhost/admin/structure/views/view/ckeditor_comments
* the custom entity is fieldable
* includes administration, permissions, Views integration
* ckeditor_comment entities have these properties:
    * cke_cid: id of the ckeditor_comment entities
    * type: type of the ckeditor_comment (the "bundle")
    * uid: uid of the author
    * title: do you need this?
    * summary
    * created
    * changed
    * target_type: type of target entity (“node”)
    * target_entity_id: id of target entity ($node->nid)
    * target_entity_revision_id: version id of target entity ($node->vid)
    * Do you need anything else? Or you're going to add other data as fields?
* see example.php for some examples on how to programmatically CRUD the entities; you can also use the entity API wrapper (see http://www.trellon.com/content/blog/creating-own-entities-entity-api)