Add explicity ruby 2.1 support

Various parts of the backtrace rewriting code require an explicit
version of Ruby to be set, which requires hard coding for every minor
Ruby release.

Going forward we should reverse the check in `instance_exec.rb` to
target older ruby versions not newer ones

Conflicts:
	cucumber.yml
	lib/cucumber/core_ext/instance_exec.rb
	lib/cucumber/platform.rb
Introduce f39a407bf2f27ef4c82e991542109a827ab1665b for v1.3.x
Deal with ruby 2.1 bug 92185 on v1.3.x
Include ruby 2.1 in the build
Merge branch 'add-21-support-to-13' into v1.3.x-bugfix

* add-21-support-to-13:
  Include ruby 2.1 in the build
  Deal with ruby 2.1 bug 92185 on v1.3.x
  Introduce f39a407bf2f27ef4c82e991542109a827ab1665b for v1.3.x
  Add explicity ruby 2.1 support
Update history
Bump version to 1.3.11
Use `MultiTest` to select best assertion library.
Use version of multi_test without 1.8.7 issues
Release 1.3.12
Background fails -> rerun formatter includes all scenarios

Let the rerun formatter includes all scenarios in the feature if the
background fails. It is realized by changing the rerun formatter to
also include skipped scenarios.
Merge pull request #654 from brasmusson/rerun-background-failure-v1.3.x

Let the rerun formatter includes all scenarios when the background fails (v1.3.x)
set upper bound for rake's version

rake 10.2.0 requires ruby 1.9 and newer but we still support 1.8
History updated
version bumped up 1.3.13
Fix undefined method `status' error in the rerun formatter

The rerun formatter should not call status on
Cucumber::Ast::ScenarioOutline elements.
Background fails -> rerun formatter includes all example rows

Let the rerun formatter includes all example rows for a sceanrio outline
if the background fails.
Merge pull request #661 from brasmusson/rerun-background-outline-failure-v1.3.x

Fix #660 and let the rerun formatter include all examples rows when the background fails
Release 1.3.14
Remove call to rspec-core internals from rspec/doubles.rb

RSpec::Core::MockFrameworkAdapter is not intended to be used outside
rspec-core itself, RSpec::Mocks::ExampleMethods should fulfil the
same purpose.

See rspec/rspec-core#1480