Add JRuby to travis tests
Add simpler syntax to matching using #on method

Following syntax is now supported:

match(value,
      on(AMatcher.(any), static_value),
      on(AMatcher.(any)) { compute_dynamic_value },
      on(AMatcher.(any)) do
        compute_dynamic_value
      end)

or a more obscure one:

match value,
      (on AMatcher.(any), static_value),
      (on AMatcher.(any) do
        compute_dynamic_value
      end)
bump v0.3.3