Use an HTTP GET rather than a POST to get user info from Tumblr.

git-svn-id: https://plugins.svn.wordpress.org/tumblr-crosspostr/trunk@875646 b8457f37-d9ea-0310-8a92-e5e31aec5664
New "detailed debugging" option to toggle lots of debug info to user.

git-svn-id: https://plugins.svn.wordpress.org/tumblr-crosspostr/trunk@875647 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update `.pot` file, readme, version bump to 0.7.8.4.

git-svn-id: https://plugins.svn.wordpress.org/tumblr-crosspostr/trunk@875648 b8457f37-d9ea-0310-8a92-e5e31aec5664