Adding VersionPrinter and tests.
making all pathing for cli local in tests for easier fork testing
running go fmt
Merge remote-tracking branch 'parent/master'

Conflicts:
	cli_test.go
	flag_test.go
Tweaking tests, removing local import.
Merge pull request #98 from jmervine/master

Exposing 'VersionPrinter'
Minor README tweaks
Merge pull request #134 from Zearin/patch-1

Minor README tweaks
Fix example code
Merge pull request #137 from nyushi/fix-example-code

Fix example code
Make -v, --version optional
Merge pull request #147 from peterbourgon/master

Make -v, --version optional