Package dist fix&test

[rooterkyberian]

So current version (0.4) on pypi cannot be installed with pip anymore, this fixes this problem and adds a check that should prevent similar problem in the future (hopefully).

Also sorry, as it seems it was my change that introduced this problem in the first place.

$ pip install monero-python                                                                                                               

Collecting monero-python
  Using cached https://files.pythonhosted.org/packages/bf/de/f9276058947553076f9395fc45aeaa6fc64d767d32b4015e195d0bf44b9a/monero-python-0.4.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-build-2t3jbry0/monero-python/setup.py", line 35, in <module>
        tests_requires=open('test_requirements.txt', 'r').read().splitlines(),
    FileNotFoundError: [Errno 2] No such file or directory: 'test_requirements.txt'

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-build-2t3jbry0/monero-python/
You are using pip version 9.0.3, however version 10.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

[coveralls]

Pull Request Test Coverage Report for Build 11

• 12 of 13 (92.31%) changed or added relevant lines in 1 file are covered.
• 9 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+1.1%) to 85.845%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
monero/base58.py	12	13	92.31%
<!--	Total:	12	13	92.31%	-->

Files with Coverage Reduction	New Missed Lines	%
monero/transaction.py	1	95.24%
monero/base58.py	1	93.0%
monero/numbers.py	2	97.62%
monero/ed25519.py	5	69.9%
<!--	Total:	9		-->

Totals
Change from base Build 1:	1.1%
Covered Lines:	843
Relevant Lines:	982

---

💛 - Coveralls

[rooterkyberian]

Coveralls decided that adding additional python 3 build meant python 2 coverage was reduced... To bribe it I have also took upon myself to improve base58 module and its coverage.