chore(lerna): update versioning flow

[austingreendev]

Description

This PR modifiers our versioning process to handle the following:

• Allow a publisher to select a new semantic version for all packages
• Generate a consolidated changelog based on pull requests that contain customizable PR labels
• Allow modification of this generated changelog diff
• Publish this changelog diff as a draft Github release
  • This gives us a chance to "publish" the release when necessary
  • Since releases trigger notifications this is the "standard" way of handling it 🤷‍♂
• Insert the changelog diff into the root CHANGELOG and publish it to master
  • This step uses [skip ci] to avoid a Travis run

Detail

There is a new version.sh script and some related utilities. I have also pinned our version in lerna to v5.0.0 to allow the first major bump to be v6!

TODO

• It will still be useful to remove some of the semantic formatting in our commit messages, but I would like to wait to add that as it will add some complexity to this process. We should be able to add another node script into version.sh to handle this formatting

[coveralls]

Coverage remained the same at 94.752% when pulling 3919ec8 on agreen/versioning-changes into 7f93c8f on master.