Suppressing errors on request domains.

Feature request: postmanlabs#1918
Introduced a new command line argument named supressRequestErrors to
newman cli. The new argument will receive a array of domain names to
be ignored of their errors (DNS lookup errors). The Run Summary
instance will suppress the errors if the errored url / domain is
supplied by the user in this argument.

bin/newman.js

@@ -43,6 +43,8 @@ program
         ' and whether to end the run with an error based on the optional modifier', util.cast.csvParse)
     .option('--ignore-redirects', 'Prevents Newman from automatically following 3XX redirect responses')
     .option('-x , --suppress-exit-code', 'Specify whether or not to override the default exit code for the current run')
+    .option('--suppress-request-errors [hostnames]', 'Specify the hostnames to be ignored on request errors',
+        util.cast.csvParse, [])
     .option('--silent', 'Prevents Newman from showing output to CLI')
     .option('--disable-unicode', 'Forces Unicode compliant symbols to be replaced by their plain text equivalents')
     .option('--color <value>', 'Enable/Disable colored output (auto|on|off)', util.cast.colorOptions, 'auto')

lib/run/summary.js

@@ -38,6 +38,13 @@ RunSummary = function RunSummary (emitter, options) {
          */
         globals: _.get(options, 'globals'),
 
+        /**
+         * Hostnames ignored during the run failures
+         *
+         * @type {VariableScope}
+         */
+        suppressRequestErrors: _.get(options, 'suppressRequestErrors'),
+
         /**
          * Holds information related to the run.
          */
@@ -370,6 +377,9 @@ _.assign(RunSummary, {
             // push failures sent from "before" events
             emitter.on(event, function (err, o) {
                 if (!err) { return; }
+                else if (_.isEqual('Error', err.name) && _.includes(summary.suppressRequestErrors, err.hostname)) {
+                    return;
+                }
 
                 var item = o && o.item,
                     source = event;