Fix typo in yaws_sendfile module
Fix mime_types.erl generation for a local installation of Yaws

Without this fix, at the Yaws startup, the mime_types.erl generation fails
on windows when Yaws is installed using the installer. It also fails for
Yaws releases built with reltool (using rebar or autotools).

Fix issue #161.
Remove authmod_gssapi from the module list in src/Makefile

This module was moved a long time ago in example/src.