Add --loglevel validation for run and build

Author: emizzle

lib/cmd.js

@@ -88,7 +88,7 @@ class Cmd {
     program
       .command('build [environment]')
       .option('--logfile [logfile]', 'filename to output logs (default: none)')
-      .option('--loglevel [loglevel]', 'level of logging to display ["error", "warn", "info", "debug", "trace"] (default: debug)')
+      .option('--loglevel [loglevel]', 'level of logging to display ["error", "warn", "info", "debug", "trace"]', /^(error|warn|info|debug|trace)$/i, 'debug')
       .description('deploy and build dapp at dist/ (default: development)')
       .action(function (env, _options) {
         _options.env = env || 'development';
@@ -107,7 +107,7 @@ class Cmd {
       .option('--nodashboard', 'simple mode, disables the dashboard')
       .option('--no-color', 'no colors in case it\'s needed for compatbility purposes')
       .option('--logfile [logfile]', 'filename to output logs (default: none)')
-      .option('--loglevel [loglevel]', 'level of logging to display ["error", "warn", "info", "debug", "trace"] (default: debug)',)
+      .option('--loglevel [loglevel]', 'level of logging to display ["error", "warn", "info", "debug", "trace"]', /^(error|warn|info|debug|trace)$/i, 'debug')
       .description('run dapp (default: development)')
       .action(function (env, options) {
         embark.run({