* Consistent license message for all the go files
* Fixing the last set of unconsistencies with the license headers
* Addressing PR review comments
* Fixing busy.go and busy_test.go license header
* fix posts returned from unread API when the list contains parent post/s
* add ExtendAll to PostList and update test per feedback
* revert unintentional change to the other test and fix comment
* update the existing postlist.Extend, filter unique values and update unit tests