bug #529 Honor --public flag given to 'yarn run dev-server ...' (lyrixx, Lyrkan)

This PR was merged into the master branch.

Discussion
----------

Honor --public flag given to 'yarn run dev-server ...'

I'm using docker (one container for the front, another one for webpack)
and I had to do this PR to make it work.

For reference, this is the command I (docker actually) executed
```
yarn run dev-server --host 0.0.0.0 --port 9999 --hot --public https://example.com:443 --disable-host-check
```

Commits
-------

5fb19de Update lib/config/parse-runtime.js
4275ff0 Honor --public flag given to 'yarn run dev-server ...'

Author: weaverryan

lib/config/parse-runtime.js

@@ -49,9 +49,19 @@ module.exports = function(argv, cwd) {
             runtimeConfig.useHotModuleReplacement = argv.hot || false;
             runtimeConfig.devServerKeepPublicPath = argv.keepPublicPath || false;
 
-            var host = argv.host ? argv.host : 'localhost';
-            var port = argv.port ? argv.port : '8080';
-            runtimeConfig.devServerUrl = `http${runtimeConfig.devServerHttps ? 's' : ''}://${host}:${port}/`;
+            if (typeof argv.public === 'string') {
+                if (argv.public.includes('://')) {
+                    runtimeConfig.devServerUrl = argv.public;
+                } else if (runtimeConfig.devServerHttps) {
+                    runtimeConfig.devServerUrl = `https://${argv.public}`;
+                } else {
+                    runtimeConfig.devServerUrl = `http://${argv.public}`;
+                }
+            } else {
+                var host = argv.host ? argv.host : 'localhost';
+                var port = argv.port ? argv.port : '8080';
+                runtimeConfig.devServerUrl = `http${runtimeConfig.devServerHttps ? 's' : ''}://${host}:${port}/`;
+            }
 
             break;
     }