Renaming tests.py to test_api.py

 * Fixed not running tests.py with py.test why file name is invalid.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Fixing some problems of test_pep8

 * Append unittest.TestCase,
   why not running test_pep8 with "python setup.py test".
 * Append tests_require to setup.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Changing test directory path

 * Changed "anydo_tests/" to "anydo/tests/".
   - No "tests/" why "tests" conflict other python packages.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Append prepare pre-commit hook

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>