Upgrade bamboo-scp-plugin to use SSHJ 0.12.0

SSH server "OpenSSH_6.7p1 Debian-5, OpenSSL 1.0.1k 8 Jan 2015" is not compatible with SSHJ 0.10.0 which bamboo-scp-plugin uses now, so some clients may have problems with SSH and SCP tasks when try to get to server.

Issue is solved at SSHJ 0.12.0: https://github.com/hierynomus/sshj

Workaround: use Script task to upload files to this server