Sendgrid-python: Code coverage

[andriisoldatenko]

Issue Summary

Add code coverage using coverage.py and https://codecov.io

Steps to Reproduce

1. Install coverage
   pip install coverage
2. Create .coveragerc
   ```cat .coveragerc
   [run]
   branch = True
   source = sendgrid, tests
   omit = site-packages

2. Run tests with coverage `coverage run -m unittest`
3. See `coverage report`

Name Stmts Miss Branch BrPart Cover

sendgrid/__init__.py 3 0 0 0 100%
sendgrid/helpers/__init__.py 0 0 0 0 100%
sendgrid/helpers/inbound/__init__.py 2 0 0 0 100%
sendgrid/helpers/inbound/app.py 23 5 4 1 70%
sendgrid/helpers/inbound/config.py 31 4 8 2 74%
sendgrid/helpers/inbound/parse.py 69 42 22 1 33%
sendgrid/helpers/inbound/send.py 28 28 0 0 0%
sendgrid/helpers/mail/__init__.py 1 0 0 0 100%
sendgrid/helpers/mail/mail.py 532 39 196 53 87%
sendgrid/sendgrid.py 22 2 0 0 91%

sendgrid/version.py 2 0 2 0 100%

TOTAL 713 120 232 57 79%
```

1. Also you can add https://codecov.io to run on each PR

Technical details:

• sendgrid-python Version: master
• Python Version: 3.5

[thinkingserious]

Thanks @andriisoldatenko,

We have added this to our backlog.

[meahow]

I would like to have a look at this, if it's still open.

[mbernier]

@meahow do it!!

[meahow]

Thanks. Hope it helps