feature #380 Add alias prod for production command (vince83110)

This PR was squashed before being merged into the master branch (closes #380).

Discussion
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Add alias prod for production command

Very simple PR, everytime I write `yarn run encore prod` instead of `yarn run encore production`, I guess it's because we use _dev_ for _development_.

I kept the `production` command of course.

Commits
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5c06db9 Add alias prod for production command

Author: weaverryan

bin/encore.js

@@ -64,7 +64,7 @@ if (runtimeConfig.useDevServer) {
 }
 
 function showUsageInstructions() {
-    const validCommands = ['dev', 'production', 'dev-server'];
+    const validCommands = ['dev', 'prod', 'production', 'dev-server'];
 
     console.log(`usage ${chalk.green('encore')} [${ validCommands.map(command => chalk.green(command)).join('|') }]`);
     console.log();

lib/config/parse-runtime.js

@@ -34,6 +34,7 @@ module.exports = function(argv, cwd) {
             runtimeConfig.verbose = true;
             break;
         case 'production':
+        case 'prod':
             runtimeConfig.isValidCommand = true;
             runtimeConfig.environment = 'production';
             runtimeConfig.verbose = false;