Avoid calling nonexistent methods on nil.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Start implementing specs for the netmask processor.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Add a Rakefile.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Add coverage checking for specs.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Add basic tests for Postfix filter processor.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>