Use Marshal.dump/load instead of YAML for speed improvements

Benchmarks from the learnup test suite:

w/ YAML:

  first run:

    Scotts-MacBook-Air-5:web(master) smtlaissezfaire$ zeus rspec spec/models/job_interests_spec.rb
    [deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
    .........................................................................................................
    Finished in 1 minute 33.93 seconds
    105 examples, 0 failures

    Randomized with seed 0

  second run:

    Scotts-MacBook-Air-5:web(master) smtlaissezfaire$ zeus rspec spec/models/job_interests_spec.rb
    .....[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
    ....................................................................................................
    Finished in 1 minute 15.73 seconds
    105 examples, 0 failures

    Randomized with seed 0

w/ BSON::Binary.new(Marshal.dump()) / Marshal.load(instrumentation['args'].to_s):

  first run:
    Scotts-MacBook-Air-5:web(master) smtlaissezfaire$ zeus rspec spec/models/job_interests_spec.rb
    .........................................................................................................
    Finished in 1 minute 21.42 seconds
    105 examples, 0 failures

    Randomized with seed 0

  second run:

    Scotts-MacBook-Air-5:web(master) smtlaissezfaire$ zeus rspec spec/models/job_interests_spec.rb
    .....[deprecated] I18n.enforce_available_locales will default to true in the future. If you really want to skip validation of your locale you can set I18n.enforce_available_locales = false to avoid this message.
    ....................................................................................................
    Finished in 1 minute 1.69 seconds
    105 examples, 0 failures

    Randomized with seed 0
bump to 0.1.7