MDS-432: app's io-loops are stopped in app d-tor

Proxy destroys elliptics io-loop to stop handlers processing before
being destroyed itself
Merge branch 'feature-mds-432' into development
Version up to 0.77.1
Elliptics sessions are destroyed before node
Merge branch 'feature-mds-432' into development
Merge branch 'development' into release-0.77
Version up to 0.77.2