Implement Container::console()

Implement Container::console()

[Feature]       An ability to connect to a PTY given to the container
[Cause]         To be able to use the container
[Solution]      Use PTYs, connect to them and pass read/writes between
                stdin/stdout and pty master.
[Verification]  There is a simple test program in junk for now

Additional changes with patchset:
- extended signal functions
- fixed signalFD class

Change-Id: Ia6320ee32d537311ef2675eb79f3e837192251b8