Bump version to 1.7.0 and update CHANGELOG

Update eventmachine dependency version requirements to be less strict.

Fix gemspec.

Bump version.

Downgrade Rack required version back to 1.0 to work w/ prior Rails ve…

…rsions.

Also name version 1.6.1 Death Proof.

Update deps to Rack >= 1.5 and EventMachine >= 1.0

Update changlog and bump version.

Version 2.0.0.pre

Raise an error when no PID file.

Fix error when sending USR1 signal and no log file is supplied.