Stability improvements for the 3.1.0 release

This release candidate brings improved stability and code quality.

Major changes:

• Exception handling on the retry loop level, works as a fallback for unknown errors (when you plug out the internet connection or kill some processes, then you never know in which moment the code execution will be)
• Migrated from complex bash piping scripts into ip route output parser, it's now a lot more safe and more independent of operating system
• Increased code coverage a little bit
• The internal SSH connection for gathering the information about remote host is now retrying the connection in case of any error, not just two selected
• Extracted methods from TunnelManager and created SystemProcessManager from them
• Rewritten connection retry method from recursion into loop. A complex recursion can cause a stack overflow