Bump Kotlin version to 1.2.51
Bump Kotlin version to 1.2.51

Summary: Pull Request resolved: https://github.com/facebook/litho/pull/405

Differential Revision: D9013683

Pulled By: passy

fbshipit-source-id: de24f0c0ec2cca6383afea0a4d89ed9854b6c62b

facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho,facebook/litho