Merge pull request #9 from optimizely/vignesh/fix-typos-changelog

Fix some typos in CHANGELOG and make it a markdown file

Author: Vignesh Raja

CHANGELOG

@@ -0,0 +1,10 @@
+## 0.1.70
+
+- Adds a `UserExperimentRecord` interface
+    - Implementors will get a chance to save and restore activations during bucketing
+    - Can be used to make bucketing persistent or to keep a bucketing history
+    - Pass implementations to `Optimizely.Builder#withUserExperimentRecord(UserExperimentRecord)` when creating `Optimizely` instances
+
+## 0.1.68
+
+- Beta release of the Java SDK for server-side testing