Bring in #assert_empty for more-helpful test output
Switch to a ternary expression for conciseness

Also, jokes
Finish writing up notes from my 1.8.6-compat testing
Print the ruby version before tests to keep myself sane
Make `rake test` do the pre-flight tasks like `rake` does

Some tools like RVM default to `rake test`, so it's easier if that
task does the right thing. Also, it's nice to be able to refer to the
main task by name so you can use it as an argument on the command
line, etc.
Better rake task description
Fix up error message a bit
RCov out, SimpleCov in
All JRuby test runners need --debug for SimpleCov to be accurate
Fix tests for FakeWeb's warnings by hiding noise from new gems

Also, move that method out of the test file.
Add a `rake clean`
Upgrade Bundler on Travis if it's old or unstable

(I'm seeing a worker with a copy of 1.3.0pre8 experience test failures
because it prints some warnings that were fixed by 1.3.0 final:
https://travis-ci.org/chrisk/fakeweb/jobs/7085551)
Work around a warning introduced in the current multi_json release