SharePoint connector fix for CONNECTORS-901

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1571120 13f79535-47bb-0310-9956-ffa450edef68
Catch content-type parse exception and deal with it locally

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1571121 13f79535-47bb-0310-9956-ffa450edef68