- Added spanish language

git-svn-id: https://plugins.svn.wordpress.org/wp-sms/trunk@991972 b8457f37-d9ea-0310-8a92-e5e31aec5664
- Updated readme.txt

git-svn-id: https://plugins.svn.wordpress.org/wp-sms/trunk@991976 b8457f37-d9ea-0310-8a92-e5e31aec5664