(PUP-2986) Add MIT license for Unknownr

 - To make COM calls over FFI to access task scheduler APIs, we
   integrated pieces of the Unknownr library and modified them for our
   particular use case.  Add attribution for this.
Merge pull request #75 from Iristyle/ticket/master/PUP-2986-add-Unknownr-MIT-license

(PUP-2986) Add MIT license for Unknownr