Fixes xetorthio/jedis#758
Conflicts:
	src/main/java/redis/clients/jedis/Pipeline.java
Add unit tests to check pipeline sync without any commands
Updated fix to xetorthio/jedis#758
Conflicts:
	src/main/java/redis/clients/jedis/Pipeline.java

With borrowing Queueable.getPipelinedResponseLength() from 3.0.0
Merge branch '2.7' of github.com:xetorthio/jedis into 2.7