Update License text in code headers with Standard BSD
Update License text in code headers with Standard BSD

Summary: Pull Request resolved: https://github.com/facebookincubator/LogDevice/pull/25

Reviewed By: Zepheus

Differential Revision: D8781582

Pulled By: calebmarchent

fbshipit-source-id: 88909ca029ded0f63cc46c881068e1c3bd1bfe48

facebook/wangle,facebook/wangle,facebook/wangle