This also removes the need for default config file.

I propose this change because:

• cpplint.py covers these Google style-like checks (things like using explicit on a constructor with one argument)
• these are often false positives, and need to be suppressed, but the suppression mechanism (// NOLINT(rule)) is problematic because the name of the rules are different for cpplint.py and clang-tidy's version of the rules
• when providing multiple rules clang-tidy emits warnings that it doesn't know the rule name used by cpplint.py, causing more unhelpful warnings

The simplest solution, in my opinion, is to remove this from the default settings, rely on cpplint.py for these kinds of checks, and let individual users add the Google style checks to their on clang-tidy config files, if they wish to use them.

@nuclearsandwich FYI