[Fix #1000] Support modifier and def on same line in IndentationWidth

Enforce an indentation style for Ruby >= 2.1 when "private def" etc
is used.
[Refactor] Shorten IndentationWidth

Needed to make it pass rubocop inspection with ClassLength/Max 121.
Merge pull request #1007 from jonas054/fix_1000_indent_after_private_def

Fix indent after private def
Add `UnneededCapitalW` cop

Add new cop `UnneededCapitalW` which detects usage of %W when
interpolation is not needed and %w would so.
[Refactor] Extract module OptionsHelp from Options

Put all help texts in one place.
[Refactor] Move methods from ConfigLoader to Config

Takes care of the code smell "Feature Envy" in ConfigLoader and
makes it smaller. Two birds with one stone.
Minor tweak
[Fix #1001] Fix --auto-gen-config logic for RegexpLiteral

A lot of different cases to consider, so more spec examples added.
Merge pull request #1013 from jonas054/fix_1001_max_slashes

[Fix #1001] Fix --auto-gen-config logic for RegexpLiteral
[Fix #993] Don't report offenses for an empty file

Except possibly for the file name.
Merge pull request #1015 from jonas054/fix_993_empty_files

[Fix #993] Don't report offenses for an empty file
[Fix #1016] Conditions don't need to be on the same line as a statement modifier
[Fix #1014] Process str nodes nested inside dstr nodes
[Fix #1011] Add pattern matching with Dir#[] for config.

But keep backwards compatibility and issue deprecation warnings for
problematic patterns such as bare file names and patterns ending with
'**'.
Merge pull request #1018 from jonas054/fix_1011_globbing

[Fix #1011] Add pattern matching with Dir#[] for config.
Fix README formatting.

For some reason, the better part of an entire paragraph became bold.
Needed to change single quotes to backticks anyway, and that also
solved the problem with bold.
Merge pull request #1019 from jonas054/fix_readme

Fix README formatting
Fix spelling error in README.md
Fix tests in the presence of `ast` 2.0.0

`AST::Node` now implements `#eql?` which allows node equality checking.
Unfortunately this is not what was intended in Rubocop, so now we must
check object identity explicitly.
Merge pull request #1023 from tamird/fix-new-parser

Fix tests in the presences of `ast` 2.0.0