automate / check copyright header

[devinrsmith]

We've got the current gradle task "licenseFormat" that applies license-header. There may be issues with this plugin. We may be able to replace w/ spotless if necessary.

Do we need to exclude certain paths?

[devinrsmith]

Simple executing ./gradlew licenseFormat changes a lot:

6,548 changed files with 17,126 additions and 3,300 deletions. 

. There are some things that probably shouldn't change, or we need to make better. For example, auto-generated code gets a new header. jpy probably shouldn't get new headers. Should Container/ get the license header?

[devinrsmith]

licenseFormat does the license header as a javadoc comment, which is not really appropriate. Will look into spotless license...

[devinrsmith]

It's also going to take some work to make sure we don't stomp over the auto-generated sources...

[chipkent]

Need to consider all of the programming languages we support.

[devinrsmith]

May be best to tackle this once #1078 merges.