Add copywrite headers to source code

[alexcnichols]

Related to #73

[cschleiden]

Is that really required? I don't really want that.

[cschleiden]

Other projects don't have this, so we shouldn't do it either.

[alexcnichols]

@cschleiden Yes. This is the standard. https://docs.opensource.microsoft.com/releasing/copyright-headers.html

Examples:

• https://github.com/microsoft/azure-repos-vscode/blob/master/src/extension.ts
• https://github.com/microsoft/azure-pipelines-vscode/blob/master/src/extension.ts
• https://github.com/microsoft/vscode-go/blob/master/src/goMain.ts

[cschleiden]

I don't see it any of the files here https://github.com/OfficeDev/office-ui-fabric-react/blob/master/packages/react-cards/src/components/Card/Card.types.ts or in rooster-js

[alexcnichols]

I don't know why various projects have or don't have these. #NotALawyer I'm doing best effort to follow the guidance from the program office to keep myself and ourselves covered.

https://github.com/microsoft/vscode/blob/master/src/main.js