Upgrade dependencies.
Add support for :cc, :bcc destinations.
Bump to 2.4.1
Bump to 2.4.0
Bump to 2.3.2
Configurable rack query parser key space limit.
Bump to 2.3.0 and release.
Bump to 2.2.4 and release.
Bump to 2.2.3 and release.
Bump to 2.2.2 and release.