Log Message:
Update ruby-listen to 3.1.5.

Restrict to ruby22 and ruby23.

v3.1.5

Bugfixes

    * #394 prevent crashes when Listen is stopped too soon (e.g. before
      being started or initialized)

v3.1.4

Bugfixes

    * #393 - relaxed rb-fsevent dependency to allow install on older OSX
      releases (thanks to @robmckinnon)

v3.1.3

Bug fixes

    * #387 - fix JRuby support both in dependencies (by allowing Ruby 2.2.3)
      and behavior (JRuby Dir.entries workaround)
    * #387 - prevent JRuby from hanging when stopping on Linux (and Travis)
    * #387 - activate JRuby-9.0.5.0 on Travis to declare support for JRuby
      (tests are flaky, but that's due to timing issues)

v3.1.2

Security enhancements

    * #377 require at least Ruby 2.2.4 to avoid CVE-2015-7551 (see
      https://www.ruby-lang.org/en/news/2015/12/16/ruby-2-2-4-released/)

Bugfixes

    * #383 allow stopping when not fully initialized (fixes guard/guard#822
      (comment))

Improvements

    * #378 warn users if their Ruby is buggy or vulnerable (controversial to
      some, but very extensively justified)

Development

    * #377 use ruby_dep for managing ruby requirements
    * #379 make RuboCop pass (thanks to @jvanbaarsen)
    * #384 avoid rubygems duplicate dependency error (gem given in both
      runtime and development dependencies)

v3.1.1

Bugfixes

    * #373 explicitly require forwardable for delegation (fixes #372)

v3.1.0

Bugfixes

    * #370 - gracefully fallback to polling on old older unsupported OSX
      versions (thanks to @vaz)

Improvements

    * #371 - update dependency to Ruby 2.2.x since 2.1 and earlier are EOL
      (minor version bumped to 3.1 in case backporting is needed)

Development

    * #371 - fix all RuboCop offenses to avoid noise during development