Update release notes for 0.3.5

CHANGELOG.md

 # Changelog
 All notable changes to this project will be documented in this file.
 
-## Unreleased
-- Updated rocksdb dependency to v5.17.2
-- Improved output of ``quarkdb-checkpoint`` command. The generated directory can now be used directly
-to spin-up a full QuarkDB node. Command aliased to ``raft-checkpoint``.
+## 0.3.5 (2018-11-28)
+- Updated rocksdb dependency to v5.17.2.
+- Improved output of backup command ``raft-checkpoint``. The generated directory
+can be used directly to spin-up a full QuarkDB node, without manual tinkering.
+Command aliased to ``quarkdb-checkpoint``.
+- Removed flood of ``attempting connection to .. `` messages when some node is unavailable.
 - Light refactoring, more widespread use of ``std::string_view``, which paves the
 way for certain performance optimizations in the future.
-- Removed flood of "attempting connection to .. " messages when some node is unavailable
+- Fixed several flaky tests.
 
 ## 0.3.4 (2018-10-09)
 - Updated rocksdb dependency to v5.15.10.