Fix Pep8 violation in unit test

[coreywright]

./tests/test_imports.py:13:1: E305 expected 2 blank lines after
class or function definition, found 1

[coreywright]

pypy-based testing in travis-ci failed because the pypy version used is too old to support the latest/2.0.3 cryptography package (which is used because secretstorage has an unbound/unpinned requirement on cryptography).

Collecting cryptography (from secretstorage->-r requirements.txt (line 6))
  Downloading cryptography-2.0.3.tar.gz (427kB)
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "app_main.py", line 75, in run_toplevel
      File "app_main.py", line 581, in run_it
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-7fwMs8/cryptography/setup.py", line 52, in <module>
        "cryptography 1.9 is not compatible with PyPy < 5.3. Please "
    RuntimeError: cryptography 1.9 is not compatible with PyPy < 5.3. Please upgrade PyPy to use this library.

the reference to cryptography 1.9 in the error message is confusing and a "bug" in the cryptography 2.0.3 codebase, imho; see https://github.com/pyca/cryptography/blob/2.0.3/setup.py#L52-L53. (i presume the pypy version requirement is still applicable to 2.0.3, even though the message references 1.9.)