processing: Add ability to specify processors per mount. The user can now specify which processors to use for each mount (i.e. each assets directory). This is mostly for disabling anything but `copy` for websites using Grunt or similar asset pipelines instead of the built-in one.

#!/bin/sh

CHEF_DIR=`dirname $0`
if `hash readlink 2>&-`; then
    LINKED_EXE=`readlink $0`
    if [ -n "$LINKED_EXE" ]; then
        CHEF_DIR=`dirname $LINKED_EXE`
    fi
fi
python $CHEF_DIR/../chef.py $@