See http://bugs.python.org/issue19995 for rationale. As micropython currently
aims for Python 3.3 compatibility I have not changed behaviour, but this
change allows the test suite to be run against a newer Python without having
spurious failures.
Tests in basics (which should probably be renamed to core) should not
rely on float, or import any non-built-in files. This way these tests
can be run when those features are not available.
All test in basics now pass on the pyboard using stmhal port, except for
string-repr which has some issues with character hex printing.
