Use the python unittest framework for tests of utils.py
Clean up PBKDF2 class

We currently include the PBKDF2 implementation from the PyCrypto author.
This patch removes some of the stuff we do not use and need. In the
future we should move to the PBKDF2 implementation that is nowadays included
in PyCrypto to clean up the code even more.
Add license header to tests and fix formating
Fix one of the SE test cases

The SE API has changed so that all the old tests will need to be fixed.
This is the first step in this direction.
Fix the rest of the Security Environment unit tests

This patch fixes the remaining Security Environment test cases so that
they will at least run. This has already turned up some
strange/inconsistent behaviour in the Security_Environment class and at
least one bug (incorrect usage of the bertlv_pack function in the
generate_public_key_pair method).
Remove PBKDF2 tests
Merge pull request #19 from d0/master

Convert most of the remaining tests to unit tests