Increase the count of ping probes

It's allowed now to get at least 3 answers for no more than 10 requests.
Pipes to grep are removed as command result is checked rather than its output.
Interval between connectivity checks is increaced (30 -> 60 sec).

Closes-Bug: #1322102

Change-Id: I0b227e3426c3d8b453986e6545829a11e125ce0b
Merge "Increase the count of ping probes" into stable/5.0