Do not delete file because streaming requests.

When doing streaming requests this file cannot be deleted on dealloc because when the HTTP request tries to get it it streamed it can already be deleted.
Convert request to streaming one because the request size when uploading videos can easily put to much memory pressure on the app.
Fix issues when blogs don't have any post on them that cause a exception because of nil predicates.
Fix answers when not a WP.com blog and no valid return is found on response.
Check if videopress is available before making videos available on picker.