3.0.3 Release

• Better tests!
  • We can determine what sniffs a "failing" sample file is expected to trigger.
  • We can tell when our sample tests collectively fail to "cover" a specific rule from our ruleset.
  • We aren't excluding some parts of ruleset from phpunit test runs because our tests live in a folder blacklisted by the ruleset itself.
• Better docs!
  • Lots of notes on testing the coding standard itself added.
• Better rules!
  • Private and protected vars/methods starting with an underscore are now reported as a warning. The sniff is valuable because "best practice" is to not use the underscore prefix, but due to the Cake 3 core still requiring this pattern in certain places, like Entities, we don't want this to be a hard error. Switching to a warning allows us to suppress them during Travis builds, while still alerting developers to the usage during local sniff runs.
  • Opening brackets are enforced again (on the same line).
  • Tabs are fully enforced.