Update readme.md
Merge pull request #437 from corysimmons/patch-1

Update readme.md
add extension setup function
document setup function
Merge pull request #435 from jenius/v3#extension-setup

"Setup" function for extensions
refactor much of the cli

- all output logs are now events so they can be toggled
- folder renamed from commands to cli
- almost all logic removed from the binary
- add usage information to roots tpl command
mock out cli test cases
add a bunch of cli tests