Issue #953: Add Tamron AF 18-270mm f/3.5-6.3 Di II VC PZD for Canon. Thanks goes to Pekka Sarnila for the patch.

git-svn-id: svn://dev.exiv2.org/svn@3250 b7c8b350-86e7-0310-a4b4-de8f6a8f16a3