Changes to make the tests run on Mac

Hello people,

  I had to made the following changes to be able to run the tests on Mac, basically the changes are below

- The check for the leap_tests folder cannot use the whole path (because tempfile.mkdtemp uses different paths on different systems)
- The gpg binary is not guaranteed to be on /usr/bin/gpg and the PATH is trimmed on the tests init, so we have to detect gpg for the tests to run