Support et and mosh as alternative ssh commands

[dhharris]

Instead of just checking that the command is ssh, check whether it is any of ssh, et or mosh. This way the user won't have to press y when using sshh with these tools.

Implemented the "list membership" functionality with help from this stackoverflow post

Tested on my remote et connection and it works flawlessly

[dhharris]

ping @yudai