Add README and Templates

[titaniumbones]

Make sure this repo has the following files:

• Readme README.md
  • Repo Badges for: Github Project, Slack, License
  • 1-3 sentence description of repository contents
  • Getting Involved section
  • Development section
• License -- LICENSE
• Contributing Guidelines (minimal and pointing to org-wide) .github/CONTRIBUTING.md
• Issue Template -- .github/ISSUE_TEMPLATE.md
• GitHub Description from 1-3 sentence readme blurb

This issue forms part of a project-wide meta-issue

[titaniumbones]

Larely addressed in #5 but waiting for rewrite #8 to proceed before merging, as the status of this repo is in flux. Removing doc-sprint label & will resolve datatogether/datatogether#37 without closing this issue.