Add ability to add extra command line

rubygems.py

@@ -172,6 +172,7 @@ class Recipe(object):
                         '--no-ri',
                         '--bindir=%s' % bindir,
                     ]),
+                'EXTRA': self.options.get('gem-options', ''),
             }
             if '==' in gemname:
                 gemname, version = gemname.split('==', 1)
@@ -179,7 +180,7 @@ class Recipe(object):
                 s['OPTIONS'] += ' --version %s' % version.strip()
             else:
                 s['GEMNAME'] = gemname
-            self.run('%(GEM)s install %(OPTIONS)s %(GEMNAME)s' % s,
+            self.run('%(GEM)s install %(OPTIONS)s %(GEMNAME)s -- %(EXTRA)s' % s,
                      self._get_env())
 
         for executable in os.listdir(bindir):