Remove Ruby 1.9.3. Add Ruby 2.0.0.
Remove Ruby 1.9.3. Add Ruby 2.0.0.

Remove Ruby 1.9.3 from Travis and support as it's been EOLed since
February (about 10 months). This seems to be required now that the
`json_schema` gem is only compatible with 2+.

Add in Ruby 2.0.0 which is still supported (until February 2016) at
least.

interagent/committee