Add stable format to your CLI reporting

This issue is related to issue #7. If we (NetBeans) would like to add support for Testify, we will need CLI reporting that is stable, it means that it won't change, ideally ever. Something like --porcelain for Git commands (search e.g. for "porcelain" in git help log).

Thanks.

One more note: it would be nice, if the CLI reporting could tell more information about failures, e.g.:

Expected: Hello world!
Actual:   Goodbye world!

Thanks.

Sorry for the late response, I've been busy with other projects in the last few months. I am in the process of planning a major refactoring of the code base, to adopt more of an OO approach. I am also looking at overhauling the reporting system to make it extensible and easy to add new reports at will. I will take your suggestion in consideration and it is definitely a good idea.