Support regex in host names in proxy config

[pranavparikh]

e.g If the only difference in host names is the environment like below

{ "router" : { "host1.env1.com" : { "newHost" : "host1.env1.com", "record" : true }, "host1.env2.com" : { "newHost" : "host1.env2.com", "record" : true },

}

},

support something like

    "host1.<env>.com" : {
        "newHost" : "host1.<env>.com",
        "record" : true
    },

where can assume the value of environment passed from some command line parameter