CRM-14161 - adjust width and height of multi-select widgets on New Mailing form to handle long names.

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* CRM-14161: New Mailing form - adjust height and width of multi-select fields to better accommodate long names
  http://issues.civicrm.org/jira/browse/CRM-14161
Merge pull request #2455 from davecivicrm/CRM-14161

CRM-14161 - adjust width and height of multi-select widgets on New Maili...