Start Rumpetroll on Debian

Question

I downloaded this script: https://github.com/danielmahal/Rumpetroll

I have a Debian system, and I want start it. I installed Mongodb, and many libraries, but when I want to start the Ruby script using ./daemon.rb, the output is:

  ** Notice: The native BSON extension was not loaded. **

  For optimal performance, use of the BSON extension is recommended.

  To enable the extension make sure ENV['BSON_EXT_DISABLED'] is not set
  and run the following command:

    gem install bson_ext

  If you continue to receive this message after installing, make sure that
  the bson_ext gem is in your load path.

/usr/lib/ruby/1.9.1/rubygems/specification.rb:1637:in `raise_if_conflicts': Unable to activate mongo-2.0.4, because bson-1.9.2 conflicts with bson (~> 3.0) (Gem::LoadError)
    from /usr/lib/ruby/1.9.1/rubygems/specification.rb:746:in `activate'
    from /usr/lib/ruby/1.9.1/rubygems.rb:212:in `rescue in try_activate'
    from /usr/lib/ruby/1.9.1/rubygems.rb:209:in `try_activate'
    from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:59:in `rescue in require'
    from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
    from ./daemon.rb:11:in `<main>'

The local gems returned by gem query –local:

*** LOCAL GEMS ***

bson (3.0.4, 1.12.3, 1.9.2, 1.0)
bson_ext (1.12.3, 1.9.2, 1.0)
em-mongo (0.5.1)
em-websocket (0.5.1)
eventmachine (1.0.7)
http_parser.rb (0.6.0)
mongo (2.0.4, 1.9.2, 1.0)
oauth (0.4.7)
rb-readline (0.5.3)

How can I start it?