Added sshj dependency.
backend can now connect to server through ssh.
UI now has support for connecting through ssh.
Merge branch 'ssh-screen' into develop

Conflicts:
	app/src/main/java/se/alkohest/irkksome/model/api/ServerImpl.java
	app/src/main/java/se/alkohest/irkksome/model/api/ServerManager.java
	app/src/main/res/values/strings.xml