Update lib/minitest/reporters/default_reporter.rb

I had a problem with the following error when trying to run a test file individually from within RubyMine:

/Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/activesupport-3.2.9/lib/active_support/core_ext/time/calculations.rb:326:in `-': can't convert nil into an exact number (TypeError)




	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/activesupport-3.2.9/lib/active_support/core_ext/time/calculations.rb:326:in `minus_with_duration'




	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/activesupport-3.2.9/lib/active_support/core_ext/time/calculations.rb:337:in `minus_with_coercion'
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporters/default_reporter.rb:139:in `after_test'
F	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporters/default_reporter.rb:41:in `pass'
a	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:77:in `public_send'
b	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:77:in `block in trigger_callback'
u	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:76:in `each'
l	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:76:in `trigger_callback'
o	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:61:in `record'
u	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:887:in `block in _run_suite'
s	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:876:in `map'
 	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:876:in `_run_suite'
t	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:30:in `_run_suite'
e	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:863:in `block in _run_suites'
s	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:863:in `map'
t	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:863:in `_run_suites'
s	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-reporters-0.13.1/lib/minitest/reporter_runner.rb:22:in `_run_suites'
 in 0.165924s, 36.1611 tests/s, 6.0269 assertions/s.
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:836:in `_run_anything'




	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:1025:in `run_tests'
6 tests, 1 assertions, 0 failures, 0 errors, 0 skips	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:1012:in `block in _run'
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:1011:in `each'
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:1011:in `_run'
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:1000:in `run'
	from /Users/mcowden/.rvm/gems/ruby-1.9.2-p290@ruby1.9/gems/minitest-4.1.0/lib/minitest/unit.rb:758:in `block in autorun'
Coverage report generated for Unit Tests to /Users/mcowden/Development/bna/bas/test/models/coverage. 0 / 0 LOC (0.0%) covered.
Add handling for when runner.test_start_time is nil

When running in an older version of minitest, our selenium
integration (based on MiniTest::Spec) does not call #before_test
before calling #print_test_with_time for the first time.
Defaulting test_start_time to Time.now does not seem to effect
the rest of the test run, and times are reported correctly.
Merge branch 'master' of https://github.com/wanelo/minitest-reporters into develop
Fix the test_start_time bug in all other reporters.
Bump version.
Make JUnitReporter compatible with Ruby < 1.9.3.

IO.write is a new method as of Ruby 1.9.3, so use File.open and << instead.
Merge pull request #48 from randycoulman/junit-reporter-compatibility

Make JUnitReporter compatible with Ruby < 1.9.3.
Bump version.
Wait until after teardown to invoke callbacks.
Bump version.
Add JUnitReporter to the list of reporters in the README
Remove 'see below' note from README since there doesn't seem to be anything below that's relevant to this line
Merge pull request #50 from carols10cents/readme_improvements

Readme improvements
Explicitly load the forwardable library
Merge pull request #51 from ferrous26/patch-1

Explicitly load the forwardable library
Bump version.
Require parallel-each to make it work
Only require ParallelEach for >= 4.2.
Use a monkey patch for (before|after)_test hooks.
Bump version.