with-readline 0.1.1 (new formula)

Adds a formula for with-readline which adds readline support to tools
that don't have readline support like the OSX native sftp.

This depends on readline and fooling about with {C,LD}FLAGS was the
way I figured out to make this build. Criticism appreciated.
Homebrew automatically sets `-I` in CFLAGS and `-L` in `LDFLAGS`.