Convert batch parameters to uppercase

listBatchSubscribe throws an 'Invalid Email Address' error when using
the lowercase 'email' batch parameter. Documentation for v1.3 API
suggests using the uppercase key name 'EMAIL'
http://apidocs.mailchimp.com/api/1.3/listbatchsubscribe.func.php . For
consistency, I've updated the other 4, although it isn't necessary.
Merge pull request #1 from errorsmith/bug/listBatchSubscribe

Convert batch parameters to uppercase