unleash-client-java-6.1.0

• 58929b78 - [maven-release-plugin] prepare for next development iteration
• 773dbe88 - Task/adhere to newest client spec (#173)
• cd5b8d15 - fix: OkHttp implementation needs to check network response for actual… (#171)
• fd91f29c - task: Add an OkHttpMetricsSender (#165)
• 1533b4b2 - fix: lock resource encoding to utf-8
• a55f6d24 - fix: clean encoding configuration
• f6889aab - [maven-release-plugin] prepare release unleash-client-java-6.1.0