Fixes #15 Issue with POP3/IMAP on Exchange 2010

Added addParam() function to use it in the imap_open call
Added function unit tests

Example of use:
$server = new Server('example.com', '143');
$server->addParam('DISABLE_AUTHENTICATOR', 'GSSAPI');
Merge pull request #1 from aleherse/master

Fixes #15 Issue with POP3/IMAP on Exchange 2010