Added acceptance tests for more CPU-architectures. Added acceptance tests for PE-files for x86.

* Added feature to compiler test cases with more than one compiler. Added clang as first examples. Fixed test cases to work with gcc

* Added acceptance tests for clang x64, adjusted Travis scripts (now
runs also unittests), install_cross_compilers installs also clang.

* Skips test for cwe415, which is broken on clang + Ubuntu 16.04

* Added feature to compiler test cases with more than one compiler. Added clang as first examples. Fixed test cases to work with gcc

* Added acceptance tests for clang x64, adjusted Travis scripts (now
runs also unittests), install_cross_compilers installs also clang.

* Skips test for cwe415, which is broken on clang + Ubuntu 16.04

* Added change to CHANGES.md

* Fixed test issue: test for json output was pre-compiler suffix.

* Initial version of CWE560 check

* CWE560 identifies calls to umask, missing the check of the umask calls.

* Initial version of CWE560 check

* CWE560 identifies calls to umask, missing the check of the umask calls.

* [cwe560] works for x64, fix function check_umask_call to detect on
other arches

* Initial version of CWE560 check

* CWE560 identifies calls to umask, missing the check of the umask calls.

* Initial version of CWE560 check

* [cwe560] works for x64, fix function check_umask_call to detect on
other arches

* Now working on the other architectures

* Refactored version of check for CWE 560 that work on several architectures. Added first unit tests for the checkers code base

* Fixes some dune warnings.

* Added CWE 560 to CHANGES.md. Fixes another dune warning.

* Requested change: Private module as a wrapper for unit tests

[Refactoring] Improves code quality of acceptance tests: use self.assertEqual instead of plain asserts