Serving stop periodically reloading feature specification after a while #188

Expected Behavior

Serving will periodically reload feature spec by calling core

Current Behavior

After a while serving is not reloading its feature spec cache

Steps to reproduce

Run feast normally and observe number of get features from serving to core is zero after awhile

Specifications

• Version: 0.1.0 , 0.1.1
• Platform: any
• Subsystem: Serving