Improve various Phame UI things

Summary:

• Clean up the menu selection states.
• Nuke some unused code.
• Show some more contextual error messages.
• Improve/pht() some strings.

Test Plan: Looked at post/blog list, empty state of "new post".

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T1373

Differential Revision: https://secure.phabricator.com/D3706