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
Update History.md
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.
Integrate with new hooks model in core.

This involved some significant changes to the legacy
formatter, because when a hook step describes its source, it will not
describe any background that the feature has. This means that if you
print a scenario as soon as you hear about it, you may be printing it
prematurely, since the scenario is just information about the hook, but
not the next node to be printed.

What I've done is to cache the parent nodes of a step like scenario, background,
scenario outline, examples table etc and only print the parents when the
step is printed.

I've also added some more test cases to the legacy formatter specs.
Refactor, make HiddenBackgroundPrinter more conventional