Twitter-oss: Prepare OSS libraries for release 18.9

Problem

We want to release the next versions of our Twitter OSS libraries 18.9
 - util
 - scrooge
 - finagle
 - twitter-server
 - finatra

Solution

Prepare libraries for their next releases.

JIRA Issues: CSL-6957

Differential Revision: https://phabricator.twitter.biz/D213029

CHANGELOG.rst

@@ -8,6 +8,9 @@ in commits.
 Unreleased
 ----------
 
+18.9.0
+------
+
 Added
 ~~~~~
 

README.md

@@ -1,7 +1,7 @@
 # Finatra
 
-[![Build Status](https://secure.travis-ci.org/twitter/finatra.png?branch=develop)](https://travis-ci.org/twitter/finatra?branch=develop)
-[![Test Coverage](https://codecov.io/github/twitter/finatra/coverage.svg?branch=develop)](https://codecov.io/github/twitter/finatra?branch=develop)
+[![Build Status](https://secure.travis-ci.org/twitter/finatra.png?branch=master)](https://travis-ci.org/twitter/finatra?branch=master)
+[![Test Coverage](https://codecov.io/github/twitter/finatra/coverage.svg?branch=master)](https://codecov.io/github/twitter/finatra?branch=master)
 [![Project status](https://img.shields.io/badge/status-active-brightgreen.svg)](#status)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/com.twitter/finatra-http_2.12/badge.svg)][maven-central]
 [![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/twitter/finatra)

build.sbt

@@ -4,7 +4,7 @@ import scoverage.ScoverageKeys
 concurrentRestrictions in Global += Tags.limit(Tags.Test, 1)
 
 // All Twitter library releases are date versioned as YY.MM.patch
-val releaseVersion = "18.9.0-SNAPSHOT"
+val releaseVersion = "18.9.0"
 
 lazy val buildSettings = Seq(
   version := releaseVersion,

project/plugins.sbt

@@ -3,7 +3,7 @@ resolvers ++= Seq(
   Resolver.sonatypeRepo("snapshots")
 )
 
-val releaseVersion = "18.9.0-SNAPSHOT"
+val releaseVersion = "18.9.0"
 
 addSbtPlugin("com.twitter" % "scrooge-sbt-plugin" % releaseVersion)