Minor Refactoring to `NumberHelper#number_to_human`

* Use destructive `map` and `sort_by` to save extra object creation.
* Create `INVERTED_DECIMAL_UNITS.invert` constant instead of repeatedly doing `DECIMAL_UNITS.invert`
read the association instead of sending
Merge pull request #12534 from vipulnsward/minor_number_helper_perfs

Minor Refactoring to `NumberHelper#number_to_human`
Added --model-name option scaffold_controller_generator.
Merge pull request #11432 from yalab/generate_model_name_option

Add --model-name option into scaffold_controller generator
Prepare generated Gemfile for Capistrano 3

Capistrano 3 is now rails-less, so we need to encourage developers to use capistrano-rails gem.

More details: http://www.capistranorb.com/documentation/frameworks/ruby-on-rails/

[ci skip]
Add missed require making `enable_warnings` available
Merge pull request #12543 from route/missed_require

Add missed require making `enable_warnings` available
Merge pull request #12524 from kirs/patch-1

Prepare generated Gemfile for Capistrano 3