Facebook Android SDK 3.18

Summary: Facebook Android SDK 3.18 (see https://developers.facebook.com/docs/android/change-log-3.x/)

Test Plan: Built ZIP

Reviewers: jacl, karthiks, clang

Reviewed By: clang

Subscribers: dmmiller

Differential Revision: https://phabricator.fb.com/D1535048
Merge branch 'master' into master-no_appcompat

Conflicts:
	facebook/build.gradle
	gradle.properties