pull development deps from gemspec to gemfile

this allows ruby 1.8 and 1.9 to have the proper ruby-debug gem
specified.

also ignore the Gemfile.lock, since this is a gem.
add simple Rakefile for convenience
add simple mute feature to clean up test output
sign both query string and XML of log out requests

also specify Destination attribute, since OpenAM requires that be
present when it has log out request verification turned on
bump gem version to 0.1.20
publish pubkey for signing as well as encryption
get travis build up and running
Merge pull request #15 from phinze/sign_log_out_requests

Sign log out requests