Release 0.4.0

• Prefer alias_method

alias_method :new_name, :old_name
# vs
alias new_name old_name

Style/Alias:
  EnforcedStyle: prefer_alias_method

• Change max line length from 100 to 120

Metrics/LineLength:
  Max: 120

• Update generator so that .rubocop.yml is created in the project root rather than /config
• Add a documentation directory