Update ruby-pygments.rb to 1.1.1.

Version 1.1.1 (2016/12/28)
-----------------------------

* Suppress Ruby 2.4.0's warnings [#172](https://github.com/tmm1/pygments.rb/pull/172)
* Enable `frozen_string_literal` [#173](https://github.com/tmm1/pygments.rb/pull/173)

Version 1.1.0 (2016/12/24)
-----------------------------

* Support JRuby [#170](https://github.com/tmm1/pygments.rb/pull/170)
* Make pygments.rb thread safe [#171](https://github.com/tmm1/pygments.rb/pull/171)

Version 1.0.0 (2016/12/11)
-----------------------------

* Upgrade bundled pygments to 2.2.0-HEAD [#167](https://github.com/tmm1/pygments.rb/pull/167)
  * This includes **incompatible changes* because of upgrade of pygments.
    See http://pygments.org/ for details.
* Relax yajl-ruby dependency to "~> 1.2" [#164](https://github.com/tmm1/pygments.rb/pull/164)
* Python binary can be configured by `PYTMENTS_RB_PYTHON` env [#168](https://github.com/tmm1/pygments.rb/pull/168)
* Improved error messages when python binary is missing [#158](https://github.com/tmm1/pygments.rb/pull/158)

(taca)