removed unneeded mime_util.h and util.h includes; added comments about sending mime headers in our handlers (which may not be needed).
removed unneeded mime_util.h and util.h includes; added comments about sending mime headers in our handlers (which may not be needed).

OPENDAP/freeform_handler,OPENDAP/freeform_handler,OPENDAP/freeform_handler,OPENDAP/freeform_handler,OPENDAP/freeform_handler