Allow for no-api for Github to be a composer configuration as well as repo specific

src/Composer/Config.php

@@ -61,6 +61,7 @@ class Config
         'archive-format' => 'tar',
         'archive-dir' => '.',
         'htaccess-protect' => true,
+        'no-api' => false,
         // valid keys without defaults (auth config stuff):
         // bitbucket-oauth
         // github-oauth
@@ -317,10 +318,10 @@ class Config
 
             case 'disable-tls':
                 return $this->config[$key] !== 'false' && (bool) $this->config[$key];
-
             case 'secure-http':
                 return $this->config[$key] !== 'false' && (bool) $this->config[$key];
-
+            case 'no-api':
+                return $this->config[$key] !== 'false' && (bool) $this->config[$key];
             default:
                 if (!isset($this->config[$key])) {
                     return null;

src/Composer/Repository/Vcs/GitHubDriver.php

@@ -56,7 +56,7 @@ class GitHubDriver extends VcsDriver
         }
         $this->cache = new Cache($this->io, $this->config->get('cache-repo-dir').'/'.$this->originUrl.'/'.$this->owner.'/'.$this->repository);
 
-        if (isset($this->repoConfig['no-api']) && $this->repoConfig['no-api']) {
+        if ( $this->config->get('no-api') === true || (isset($this->repoConfig['no-api']) && $this->repoConfig['no-api'] ) ){
             $this->setupGitDriver($this->url);
 
             return;