Talker

Fixed
- parse command OSError.strerror to bytes
- fix travis build links
- start talker agent logging after configure logging
- fix travis python3.7 package installation issue
- fix is_alive function

Added
- allow stop waiting on command when the host isn't responsive
- add agent talker daemon systemd support

Changed
- log only once when reactor gets a command
- add talker details to NoResponseForRedisCommand exception

Fixed
- pass ClientCommandTimeoutError client timer elapsed time as timeout parameter

Fixed
- improve reactor pipeline execution error handling
- add missing 'bash -ce' to sync and reboot in 'reboot_host'
- make client is_alive resilient

Added
- log talker reboot stdout and stderr in case reboot didn't complete

Fixed
- support ack_timeout None value
- when killing a talker job wait until process is terminated (remove hanging job mechanism)
- handle properly corrupted seen jobs file

Fixed
- sync all files before reboot

Added
- add support for client to pass ack_timeout
- add is_alive to client api
- raise special exception on client redis connection error

Fixed
- agent syncs only reboot sentinel and log file before reboot
- make all agent threads thread-safe
- check recover from reboot only when there is no previous exception
<br/>or orphaned job