Add license injector

[dmreagan]

I recently learned of the recommendations from the IU Open Source Administrators. They include licensing with BSD-3 and inserting license and copyright info into all source files. This PR adds an npm script which automatically checks for the info and inserts it if it is missing. It can also be configured to search for and remove license info if we need to change things later.

We'll need to check with the Immersive Scholar folks to see if BSD-3 works for them.

[guangchen]

Merged license branch into master

[dmreagan]

@guangchen, it looks like you forgot to merge

[guangchen]

Need to rollback to previous commit since I found the license branch raises "Access to XMLHttpRequest at XXXX has been blocked by CORS policy" error. I suspect this is brought by some newly introduced dependencies in package.json. Dave can you please verify this issue?

[dmreagan]

Could it be a problem with the injected license info in one of the files? Like maybe it wasn't commented correctly, or there's a problem having comments at the top of the file? Please check the extra license_formats I had to provide in package.json for any mistakes. The only dependency added to package.json is the utility for injecting the license info, which only runs when you manually execute it.

[dmreagan]

Going with #57 for now. May return to this later for individual file injection.