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