Make aliases for forwarding settings

[nawa]

Original sample config

app-port: 8080
start-page: master
hosts:
    master:
        address: 10.1.1.1:8080
    worker-1-8081:
        address: 10.1.1.1:8081
        forwarding:
            server: 10.1.1.1:22
            user: ssh-username
            private-key: ~/.ssh/id_rsa
            password: #in case of password
    worker-2-8081:
        address: 10.1.1.2:8081
        forwarding:
            server: 10.1.1.1:22
            user: ssh-username
            private-key: ~/.ssh/id_rsa
            password: #in case of password

New one with aliases

app-port: 8080
start-page: master
forwarding-aliases:
    alias1:
        server: 10.1.1.1:22
        user: ssh-username
        private-key: ~/.ssh/id_rsa
        password: #in case of password
hosts:
    master:
        address: 10.1.1.1:8080
    worker-1-8081:
        address: 10.1.1.1:8081
        forwarding:
            alias: alias1
    worker-2-8081:
        address: 10.1.1.2:8081
        forwarding:
            alias: alias1