Use JLine2 and Picocli to reimplement leshan-client-demo Interactive CLI

[sbernard31]

It could be possible to use JLine3 but it needs Java 8 and for now we are stucked to Java 7. (See #924)

We move from SimpleLogger to logback to be able to implement custom TerminalAppender.
Some other reason to move to logback :

• use a log4j backend which support color (Add some colors 🌈 to output logs #568)
• use same backend for all demos

Drawback client will be clearly heavier with move to :

• picocli (instead of common-cli)
• jline (instead of nothing)
• logback (instead of SimpleLogger)

But we think that leshan-client-demo does not target so small devices and so usability improvement should worth it.

The usability improvement are :

• usage help
• autocompletion
• history / search history
• color

At code point of view, code is clearer and should be easier to maintain (e.g. adding new commands)