Update CHANGELOG and version for 1.9 release (#680)

Author: prashantv

CHANGELOG.md

@@ -1,6 +1,12 @@
 Changelog
 =========
 
+## [1.9.0] - 2018-01-31
+### Added
+ * stats: Add tally reporter to emit tagged metrics. (#676)
+ * Add optional idle timeout, after which connections will be
+   closed. (#681)
+
 ## [1.8.1] - 2017-11-21
 ### Fixed
  * Always log addresses as strings. (#669)
@@ -216,6 +222,7 @@ Changelog
 * Thrift support, including includes.
 
 [//]: # (Version Links)
+[1.9.0]: https://github.com/uber/tchannel-go/compare/v1.8.1...v1.9.0
 [1.8.1]: https://github.com/uber/tchannel-go/compare/v1.8.0...v1.8.1
 [1.8.0]: https://github.com/uber/tchannel-go/compare/v1.7.0...v1.8.0
 [1.7.0]: https://github.com/uber/tchannel-go/compare/v1.6.0...v1.7.0
@@ -235,4 +242,4 @@ Changelog
 [1.0.5]: https://github.com/uber/tchannel-go/compare/v1.0.4...v1.0.5
 [1.0.4]: https://github.com/uber/tchannel-go/compare/v1.0.2...v1.0.4
 [1.0.2]: https://github.com/uber/tchannel-go/compare/v1.0.1...v1.0.2
-[1.0.1]: https://github.com/uber/tchannel-go/compare/v1.0.0...v1.0.1
+[1.0.1]: https://github.com/uber/tchannel-go/compare/v1.0.0...v1.0.1

version.go

@@ -23,4 +23,4 @@ package tchannel
 // VersionInfo identifies the version of the TChannel library.
 // Due to lack of proper package management, this version string will
 // be maintained manually.
-const VersionInfo = "1.8.1-dev"
+const VersionInfo = "1.9.0"