Allow proxying to subdirectories with proxyUrl

Fixes #250. Closes #251.
Fix missing code coverage when running on Windows

Closes #255.
Allow users to run functional tests without running through unit tests first

Closes #241.
Add an HTML reporter and make it a default for the browser client

Fixes #103. Closes #194.

Also-by: Mangala SSS Khalsa <mkhalsa@sitepen.com>
Also-by: Jason Cheatham <j.cheatham@gmail.com>
Change suite error handling to fatal error handling in console reporter

Suite errors report as fatal errors anyway, so such failures will still
be reported.

Fixes #213.
Add Suite#timeElapsed
Fix whitespace errors
Expose error message formatting function for use by reporters
Add JUnit XML reporter

Fixes #102. Closes #193.

Also-by: Mangala SSS Khalsa <mkhalsa@sitepen.com>
Also-by: Jason Cheatham <j.cheatham@gmail.com>
Set client mode before loading realClient so configs can access it

Fixes #263.
Cannot search for error locations in environments without stack traces
Update Leadfoot and Dig Dug dependencies

Fixes #215.
Updating metadata for 2.1.0
Updating source version to 2.2.0-pre
Coerce args.functionalSuites to array

Fixes #272.
Rename `received` property due to upstream change

Fixes #265.
Allow empty suites/functionalSuites command-line args

Also ensure that the state of `args.suites` is used when determining
whether or not to run ClientSuite in the runner, since that argument
is passed to the client and decides which unit test suites execute.

Fixes #268. Closes #269.
Empty suites command-line flag should skip running client

Refs #241. Closes #270.
Update Leadfoot dependency
Update contribution guidelines

[ci skip]