Add code quality checks

[seporaitis]

Description

This sets up codecov integration with Travis-CI.

Motivation and Context

Some automated code linting should be good for code hygiene.

How Has This Been Tested?

This pull request should be checked by codecov.

Screenshots (if appropriate):

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
  • [ ] I have updated the documentation accordingly.
• [ ] I have updated HISTORY document.
  • [ ] I have referenced pull request and/or issue next to the change.
• [x] I have read the CONTRIBUTING document.
• [x] All new and existing tests passed.
  • [ ] I have added tests to cover my changes.

[seporaitis]

Seems like I misunderstood what codecov does - it checks code coverage after test run. That's fine, but we don't yet have a test suite, so I'll wait to see what LGTM integration presents in terms of security alerts and will close this.