v0.7.0

Overview

1. Support user-selected output format (e.g. Markdown-only and classic card with AdaptiveCard in the future)
2. Rename url to outputURL to remove collision with Heroku adapter

Updates

1. dep: go mod: update
2. cleanup: util/attachment.go: remove unneeded code
3. docs: README.md: update incl 401 error
4. feat: adapters: add ability to modify cards via query param
5. style: alias: remove alias; move unneeded code
6. enhance: change qryparam to outputURL from url; prep for outputFormat
7. style: alias: remove sporadically used cc alias for commonchat
8. internal: constances: enhance/consolidate constant management
9. docs: shields: add LOC