Updated changelog with post-0.7.1 updates.

Author: jdantonio

CHANGELOG.md

@@ -1,3 +1,10 @@
+### Next Release v0.7.2 (TBD)
+
+* Renamed `:overflow_policy` on thread pools to `:fallback_policy`
+* Thread pools still accept the `:overflow_policy` option but display a warning
+* Thread pools now implement `fallback_policy` behavior when not running (rather than universally rejecting tasks)
+* Test now run on new Travis build environment
+
 ## Current Release v0.7.1 (4 December 2014)
 
 Please see the [roadmap](https://github.com/ruby-concurrency/concurrent-ruby/issues/142) for more information on the next planned release.