Tagging 2.2.6: Improved Ghostscript exe detection logic

git-svn-id: http://plugins.svn.wordpress.org/document-gallery/trunk@1011833 b8457f37-d9ea-0310-8a92-e5e31aec5664
Tagging 2.2.7: Resolves a few translation-related bugs.

git-svn-id: http://plugins.svn.wordpress.org/document-gallery/trunk@1020635 b8457f37-d9ea-0310-8a92-e5e31aec5664
Resolving issue #13 -- DG_Thumber::isGoogleDriveAvailable() now returns real values rather than always true.

git-svn-id: http://plugins.svn.wordpress.org/document-gallery/trunk@1020753 b8457f37-d9ea-0310-8a92-e5e31aec5664