Update CHANGELOG for v2.1.0 (#149)

* Update CHANGELOG for v2.1.0

Author: TheIronDev

CHANGELOG.md

@@ -0,0 +1,24 @@
+## Breaking Improvements
+
+- Generated CloudEvents will use the user-provided Partial<CloudEvent> to infer other fields. #146
+  - For storage events, updating the Partial's `bucket` will update:
+    - `data.bucket`
+    - Parts of `source`, `data.selfLink`, `data.id`
+  - For PubSub events, updating the Partial's `data.message.json` will:
+    - generate a new base64 string for `data.message.data`
+      - (But a user-provided `data.message.data` still takes priority)
+
+## Full list of Changes
+- Update to README.md to include more samples #143
+- Add top-level bucket field to Mock Storage CloudEvents #145
+- Delete .travis.yml #120
+- Add CI for firebase-functions-test #147
+- Refactor MockCloudEvent generation to include user partial #146
+- Unit tests for MockCloudEvent generation refactor #150
+- Updated Dependencies
+  - Bump plist from 3.0.1 to 3.0.5 #132
+  - Bump minimist from 1.2.5 to 1.2.6 #129
+  - Bump path-parse from 1.0.6 to 1.0.7 #115
+  - Bump pathval from 1.1.0 to 1.1.1 #127
+  - Bump glob-parent from 5.1.1 to 5.1.2 #103
+  - Bump ws from 7.3.1 to 7.5.7 #133