Adds failsafe meter passing (and removes unneeded (?) dependency)

Hi,

instead of implementing `ProgressBar.new(:meter, :eta, :output => $stdout)`, I made the meter assignment failsafe.
With commit d790ecdcd3427d0dc6968fb0ed22b655faeee376 unknown meters are not taken to render the progress bar. Without that code, it's possible to cause a *method_missing* error.

Commit 58d6162906d0828cbe5270344d5fbfdbde663228 removes the dependency on the gem 'options'. It's not used at the moment.

--
Greetings, Johannes