Remove useless shebangs and executable permissions

[musicinmybrain]

Checklist

• I have read the contributing doc.
• I have included a link to the relevant issue number.
• I have tested this code locally.
• I have checked to ensure there aren't other open pull requests
  for the same issue.
• I have written new tests for these changes, as needed. N/A
• All tests pass.

While there is no issue filed for this specific change, this PR comes from discussion in #1270.

[micahellison]

Thanks for your contribution!