Change underlying SSH library

[ahitrin]

Currently, SA code is bound to the deprecated version of MindTerm library. This library also has murky license policy. It's better to totally replace it with modern and free Java SSH library, like JSch or sshj.

Migration plan is available here.

[ahitrin]

Wrote initial plan here

[ahitrin]

More libraries (need verification/testing):

• Apache SSHD - with small team, but evolving
• SSHTool -- seems to be abandoned
• Ganymed-SSH2 -- very little info found

[ahitrin]

Apache Mina could be used, at least, for testing purposes. It would be 100 times easier to migrate underlying SSH backend when having automated tests suite.

[ahitrin]

Hard to be done without #55. Prefer to implement/try #55 first

[ahitrin]

Well... current SSH implementation is way too old. It cannot even connect to new SSH servers:

Apr  4 10:17:23 ubuntu sshd[6991]: fatal: Unable to negotiate with <IP> port <PORT>: no matching key exchange method found. Their offer: diffie-hellman-group1-sha1,diffie-hellman-group1-sha14,diffie-hellman-group-exchange-sha1 [preauth]