Fix crash when adding blogs

When the user only had one blog and it's already added, trying to add
more wp.com blogs might result in a crash.

`refreshBlogs` was called on `viewWillAppear`, and it might end before
the view is fully presented. This results in popping the view controller
while it's still being animated and crashes.

Call `refreshBlogs` from `viewDidAppear` instead so the animation is
completed.
Don't reuse image pickers on editor.

It seems to be the reason of some crashes on iOS7.
Fixes display and playback issues with VideoPress videos.

Parses and formats VideoPress markup into something DTCoreText will recognize.
Grabs thumbnails for VideoPress.
Correctly strips videopress markup from post summaries.
Wrangles MPMoviePlayerViewController to not automatically dismiss when playback ends.
Skip parsing width and height for VideoPress.

Not necessary.  DTCoreText will parse the mark up fine without.
Do not use UIModalTransitionStyleCrossDissolve for the iPad.

Quick fix for some layout weirdness on the ipad when showing the modal while the keyboard is visible.