Added action to check for cURL transport and issue notification if enabled and transport is missing.

git-svn-id: https://plugins.svn.wordpress.org/wpgform/trunk@849700 b8457f37-d9ea-0310-8a92-e5e31aec5664
Prep for v0.64 release.

git-svn-id: https://plugins.svn.wordpress.org/wpgform/trunk@849701 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated language files with new strings.

git-svn-id: https://plugins.svn.wordpress.org/wpgform/trunk@849702 b8457f37-d9ea-0310-8a92-e5e31aec5664