BUG-372 Add reconnecting to netconf-connector for unexpected session drop

Netconf connector will reattempt connection if the session to remote device is dropped.
Increase sleep factor in netconf connector from 1.0 to 1.5.
This prevents connection attempt every second in case remote device is not comming back for longer time.
Connection attempts span increases gradually.

Change-Id: Icc4b993942e9cc6897c0da858eb867afa4c8aa87
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>
Merge "BUG-372 Add reconnecting to netconf-connector for unexpected session drop"