Exit on error

[Conradowatz]

This feature is meant for use in software testing pipelinies.
It would be nice to have the option for the testrun to abort and exit with an error exit code, if a test failes. This way you can integrate it within a software pipeline, that fails on an error.

A flag should be implement like -exitOnError with different levels as options: like lax, default or strict. Wheras strict could exit on every failed testcase, default only on security and interoperabillity relevant tests and lax only on security relevant tests (suggestion).

If the flag is set and a testcase failes, the program should exit with an error code of 1 and print out why it failed. (Please see #31).