Modify mockbin command to use env vars or custom npm config

bin/mockbin

@@ -6,11 +6,17 @@ var app = require('../src')
 var cmd = require('commander')
 var pkg = require('../package')
 
+var options = {
+  port: process.env.MOCKBIN_PORT || process.env.npm_package_config_port,
+  quiet: process.env.MOCKBIN_QUIET || process.env.npm_package_config_quiet,
+  redis: process.env.MOCKBIN_REDIS || process.env.npm_package_config_redis
+}
+
 cmd
   .version(pkg.version)
-  .option('-p, --port <port>', 'HTTP server port', pkg.config.port)
-  .option('-q, --quiet', 'disable console logging', pkg.config.quiet)
-  .option('-r, --redis [dsn]', 'redis dsn', pkg.config.redis)
+  .option('-p, --port <port>', 'HTTP server port', options.port)
+  .option('-q, --quiet', 'disable console logging', options.quiet)
+  .option('-r, --redis [dsn]', 'redis dsn', options.redis)
   .parse(process.argv)
 
 app(cmd, function () {