Add output mode to show test method name in addition to docstring

[jayvdb]

unittest shows test method name and docstring. nose only shows the docstring, if it exists, or the method name if it doesnt have a docstring.

https://github.com/wikimedia/pywikibot-core is searching for an advanced test runner like nose (and I am very impressed with green so far), but we'd like the output to include the test method names, so that it is easy to rerun an individual test method using its dotted.name.

The following layout would be ideal

module
  class
    method1: docstring
    method2: docstring

See https://phabricator.wikimedia.org/T115313 for our task related to this.

[CleanCut]

I absolutely agree. It's part of #30.