Update README.md

Trivial typo fix
Merge pull request #33 from ffmike/patch-1

Update README.md
Ignore ruby version file.
Get tests running on latest rails master branch for 4.1.
Rails 4.x / MiniTest 5.x Compatability.

MiniTest::Spec now uses a thread local variable to use with spec expectations. Set this just as MT:S does for AS:TC by using a simple initialize method.

* Removed some 1.8 only code.
* Removed utils to check Rails versions. Moot now.
* Use newer `assert_not` rails assertion vs deprecated/removed `assert_blank`.
Two important Rails 4.x refactors.

* Fix nested described test names along with Minitest::Spec.describe_stack. Fixed #21.
* Leverage `ActiveSupport::Testing::ConstantLookup` for our `described_class` interface.
Update CHANGELOG and prepare for 5.0.0 release.
Fix note.
Dont miss out on previous changes.
Backfill CHANGELOG>
Extend initializers with MiniTest::Spec::DSL to ensure that register_spec_type is available.

Fixes https://github.com/metaskills/minitest-spec-rails/issues/37