A few tweaks to the logging functionality.

* Addresses a few (not all) review comments from
  Maria's structured logging patch.

* Removed changeLogTypes -- setting a new logger in
  parse.js and parserTests.js where necessary.

* Updated default log types to "error" and "fatal".

* Tweaked the trace test generating regexp to add a (\/|$) check
  to all log types so that env.log("fatalities", ..) does not match
  the "fatal" logtype. All subtypes are always matched by default
  so an explicit "fatal/request" is not required in default logtypes.

* Fixed --trace output breakage by adding back checks from the
  previous patch into the default backend.

* Unrelated: arranged requires in alphabetical order in parserTests.js.

Change-Id: I0ae4d51f90dcf5e507bd509f303362c4974ae93a