Need Create_Pages capability in new roles feature set

[anotherchris]

The new capabilities rule set needs more granularity on the pages side. While there is already a ​ticket for an edit_others_pages like capability I also think things should be broken down a step further and Edit_Pages split into separate Create and Edit existing flags.

This would allow for an editor, adming or other person high up in the food chain to be solely responsible for changes to the information architecture of the site* while those who are taksed simply with writing for the site could still change the content on existing pages as needed.

• I realize that the edit pages still would have some features like editing page slug that could be changed

some more discussion of the setup i'd look to create ​in this wp-hackers thread

[ryan]

(In [3513]) Add new page caps now that pages can be draft or publish. Brings page caps to parity with posts. Add delete caps for posts and pages. fixes #2382 #2336 #2301