Few bikeshedding tasks

[hhsecond]

Description

• Twitter handle, Email link
• Gitter to Slack
• Contributing guide and changelog
• Making licensing proper
• Content for pypi

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

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