TIKA-1486 Remove duplicated mimetype defintions

git-svn-id: https://svn.apache.org/repos/asf/tika/trunk@1641628 13f79535-47bb-0310-9956-ffa450edef68
TIKA-1486 Make DITA Task be a subclass of DITA, and not of itself

git-svn-id: https://svn.apache.org/repos/asf/tika/trunk@1641630 13f79535-47bb-0310-9956-ffa450edef68