Use full path for ragel svg task
Use full path for ragel svg task

Currently the ragel:svg task is broken. We need to use the full path
because of a change to Rake in https://github.com/ruby/rake/pull/39.

We already changed this for the ragel:generate task in
https://github.com/mikel/mail/commit/20ffe29a45f96ba3bd9447571e0593f938a36c0e

mikel/mail