Add Rubocop for Ruby static code analysis
Configure Rubocop to ignore documentation warnings
Configure Rubocop to run Rails cops
Increase allowed Rubocop line length to 120 chars
Fix suppression of exceptions
Fix assignment in condition
Fix missing final newline
Fix alignment and indentation
Use the lambda method for multi-line lambdas
Favor modifier if usage given a single-line body
Prefer single-quoted strings

We don't need string interpolation or special symbols.
Remove redundant `self.` from article repository
Remove extra empty line detected at class body end
Use fail instead of raise to signal exceptions
Use %r for regexp matching more than 1 '/' char
Allow `bin/scss-lint` to not be snake case
Add Rubocop rake task
Merge branch 'rubocop'