add some extra mime types.
use mime.types from apache2

http://svn.apache.org/viewvc/httpd/httpd/trunk/docs/conf/mime.types?revision=1301894&view=co
only run if no magic.
Merge pull request #1 from BankSimple/mimefix

add some extra mime types.
Properly check for the presence of multipart files, to avoid always calling HEAD on every object.
Merge pull request #2 from tom/master

Don't call HEAD on every file yo