Drop runtime dependency on ActiveSupport due to minimum ruby requirement

[bdunne]

more_core_extensions/core_ext/object/blank.rb was copied from
https://github.com/rails/rails/blob/v5.0.0/activesupport/lib/active_support/core_ext/object/blank.rb

With the release of ActiveSupport v5.0.0 a minimum required_ruby_version
of '>= 2.2.2' was added. The code for Blank has been copied here so that
we can continue to support ruby versions that don't meet that requirement.

The test was mostly copied as well, but rewritten in rspec syntax.

ActiveSupport has been added as a development dependency for ruby >= 2.2.2
to allow for testing nested hash features with HashWithIndifferentAccess

[bdunne]

@Fryguy Please review.

cc @jrafanie @gmcculloug

[bdunne]

I'll rework ManageIQ/ovirt#57 after this is merged.

[miq-bot]

Checked commits bdunne/more_core_extensions@72af99c~...288f0d0 with ruby 2.2.5, rubocop 0.37.2, and haml-lint 0.16.1
6 files checked, 6 offenses detected

lib/more_core_extensions/core_ext/object/blank.rb

• ❗ - Line 101, Col 5 - Style/Alias - Use alias instead of alias_method in a class body.
• ❗ - Line 123, Col 26 - Style/CaseEquality - Avoid the use of the case equality operator ===.
• ❗ - Line 20, Col 30 - Style/DoubleNegation - Avoid the use of double negation (!!).
• ❗ - Line 91, Col 5 - Style/Alias - Use alias instead of alias_method in a class body.

spec/core_ext/hash/nested_spec.rb

• ⚠️ - Line 230, Col 1 - Lint/HandleExceptions - Do not suppress exceptions.
• ❗ - Line 206, Col 9 - Style/WordArray - Use %w or %W for an array of words.

[bdunne]

Not planning to make any additional rubocop changes since the majority of that code is copied.

[jrafanie]

Nice work @bdunne 👏