Generate 'Exclude' list if different styles is used

[flexoid]

If mixed styles of the specific cop is used across project files,
some of the cops (probably all style cops) now set 'Enabled: false'
regardless of the count of files with offense and "--exclude-limit" argument.

For example:

class Test
  def m1(a=1)
  end

  def m2(a = 1)
  end
end

.rubocop_todo.yml for the following ruby code was (with any --exclude-limit value):

# Offense count: 1
# Cop supports --auto-correct.
# Configuration parameters: EnforcedStyle, SupportedStyles.
# SupportedStyles: space, no_space
Style/SpaceAroundEqualsInParameterDefault:
  Enabled: false

Now it will be like this, as expected:

# Offense count: 1
# Cop supports --auto-correct.
# Configuration parameters: EnforcedStyle, SupportedStyles.
# SupportedStyles: space, no_space
Style/SpaceAroundEqualsInParameterDefault:
  Exclude:
    - 'test.rb'

With --exclude-limit 0:

# Offense count: 1
# Cop supports --auto-correct.
# Configuration parameters: EnforcedStyle, SupportedStyles.
# SupportedStyles: space, no_space
Style/SpaceAroundEqualsInParameterDefault:
  Enabled: false

And with m2 method commented:

# Offense count: 1
# Cop supports --auto-correct.
# Configuration parameters: SupportedStyles.
# SupportedStyles: space, no_space
Style/SpaceAroundEqualsInParameterDefault:
  EnforcedStyle: no_space

[jonas054]

if different styles are used

And it's not entirely correct to say that it's for style cops, because there are a handful of rails cops that have a configurable enforced style, and they will also be affected by this correction. So say "cops with configurable enforced style" instead.

[jonas054]

Code looks good. Just some remarks on the changelog entry.

[flexoid]

@jonas054 thanks for your corrections, I just fixed changelog and rebased on master.

[bbatsov]

Unfortunately you'll have to rebase this again.

[flexoid]

@bbatsov no problem, done

[bbatsov]

Are you sure? I still see a merge conflict.

[flexoid]

Master is changing so quickly :) Should be mergeable until next PR.