Test failures on Python 3

[rahulporuri]

Three test failures are seen when installing codetools from pypi in a python 3 env. Note that some of the dependencies need to be installed manually as they are not specified in the codetools setup script. See #26 .

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ERROR: Assigning floats to arrays
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Traceback (most recent call last):
  File "/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_test_case.py", line 44, in test1
    file_object = open(os.path.join(self.code_dir,'test1.py'), 'r')
FileNotFoundError: [Errno 2] No such file or directory: '/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_codes/test1.py'

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ERROR: Different sized arrays
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Traceback (most recent call last):
  File "/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_test_case.py", line 65, in test2
    file_object = open(os.path.join(self.code_dir,'test2.py'), 'r')
FileNotFoundError: [Errno 2] No such file or directory: '/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_codes/test2.py'

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ERROR: Same sized array assignments within 'with' block
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Traceback (most recent call last):
  File "/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_test_case.py", line 86, in test3
    file_object = open(os.path.join(self.code_dir,'test3.py'), 'r')
FileNotFoundError: [Errno 2] No such file or directory: '/home/rporuri/.edm/envs/temp3/lib/python3.6/site-packages/codetools/contexts/tests/with_mask_codes/test3.py'

The errors are because .../with_mask_codes/ doesn't contain an __init__ file so the test*.py files in the submodule aren't included in the sdist uploaded to pypi.

[rahulporuri]

This should be fixed along with #34 with the use of a manifest file.