Suppress offences if rhs is block node in ConstantName cop

The cop is already ignoring non SCREAMING_SNAKE_CASE name constant
assignments when rhs is a send node.
This change adds block type to the types to ignore.

This fixes #432.
Merge pull request #433 from yujinakayama/fix-constant-assignment-with-block

Suppress offences if rhs is block node in ConstantName cop
Support class/module defined with Class.new/Module.new in AccessControl

This fixes #434.
Merge pull request #436 from yujinakayama/support-class-new-in-access-control

Support class/module defined with Class.new/Module.new in AccessControl
Added `--show-cops` CLI option

* added option to cli
* extended cop to get description out of configuration
* changed default configuration to have a description field for all cops
Merge pull request #395 from dirkbolte/show_cops_option

`--show-cops` CLI option
Remove duplicated definition of Token
New cop NilComparison
New cop IndentationWidth.

Fixes #423.