1.6.7 Light Released

1.6.7 (2019-08-16)

Merged pull requests:

• Feat/connection pool #598 (jiachen1120)
• Fix/#590 skip tests #591 (BalloonWen)
• fixes #600 upgrade jackson-databind to 2.9.9.3 #601 (stevehu)
• Feat/pluggable config loader #575 (jiachen1120)