`bundle update` before upgrading rails
Don't re-create existing tags
Upgrade to Rails 4

- Upgrade to Rails 4 gems
- Updated config files
- Added
[rails/protected_attributes](https://github.com/rails/protected_attribut
es) gem but should move to
[rails/strong_parameters](https://github.com/rails/strong_parameters)
- Use `find_by` in favour of deprecated dynamic finders
- Using `double` instead of deprecated `mock`