Flagr segments evaluation should stop if it matches all the constraints in a segment

[zhouzhuojie]

Expected Behavior

If the entity context matches the constraints in a segment, it should stop evaluating the following segments.

Specifically, for 0% rollout segment, it shouldn't go to the next segments.

For example:

The first segment catches all the entity, and roll out to 0%, so every entity should have null variant returned.

Current Behavior

It falls through to the next segment for non-rolled out users in the previous segments.

Possible Solution

Stop evaluating the next segments if we found a match (i.e. satisfied all the constraints in a segment)

Steps to Reproduce (for bugs)

https://try-flagr.herokuapp.com/#/flags/1