Fix scaffold view generator templates for reference attributes

Rails generates field with an _id suffix for reference attributes, see
https://github.com/rails/rails/blob/master/railties/lib/rails/generators/erb/scaffold/templates/_form.html.erb#L24-L30

This commit should fix this case by using attribute.column_name instead of
attribute.name as used by the Rails generator template.
Invoke #column_name when available, use #name otherwise

Thanks @cupakromer for the suggestion

Note: include tests only for Rails >= 4.0.0
Setup local variable for attribute name; simpler check for Rails version

See also:

* https://github.com/rspec/rspec-rails/pull/937#commitcomment-6170626
* https://github.com/rspec/rspec-rails/pull/937#commitcomment-6170693
Remove workaround from cff02284.
Apply temp patch for Travis, RVM, and Ruby 2.1.0
Add Ruby 2.1.x and Rails 4.1.0 proper.

Use 2.1 fuzzy matching.
Attempt to force MRI 1.8.7
Add issue links for recent changes.
Merge pull request #937 from potomak/fix-scaffold-view-generator-templates

Fix scaffold view generator templates for reference attributes in Rails 4.x
Merge pull request #1015 from rspec/fix-2-1-0-build

Update `.travis.yml` to workaround CI issues.
Document the `have_http_status` matcher.

Outline the intended use cases for the `have_http_status` matcher:

- It is designed to work of "response" objects
- It should work with controller, request, and feature specs
- It allows checking against:
  - Specific numeric status codes
  - Any of the Rails provided symbolic names for status codes
  - General status code categories
Create `have_http_status` matcher.

The matchers passes if the provided actual `response`, or Capybara
`page`, has a matching HTTP status code. The following symbolic status
codes are allowed:

  - `Rack::Utils::SYMBOL_TO_STATUS_CODE`
  - One of the defined `ActionDispatch::TestResponse` aliases:
    - `:error`
    - `:missing`
    - `:redirect`
    - `:success`

The inspiration for this matcher comes directly from Rails' `assert_response`:

  https://github.com/rails/rails/blob/ca200378/actionpack/lib/action_dispatch/testing/assertions/response.rb#L22-L38

Thank you to all the Rails devs who did the heavy lifting on
`assert_response`!
Add changelog note.
Note `have_http_status` matcher in README.