Run tox in parallel and fix setup to use specific pyangbind version

Change-Id: I6f02f0137798c0d282550f8bbaa44cd499d4fefa
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/setup.py b/setup.py
index ec75988..8150d9f 100644
--- a/setup.py
+++ b/setup.py
@@ -30,8 +30,8 @@
         subprocess.call([sys.executable, "-m", "pip", "install", package])
 
     def run(self):
-        self.pipinstall('pyang')
-        self.pipinstall('pyangbind')
+        self.pipinstall('pyang==2.5.2')
+        self.pipinstall('pyangbind==0.8.1')
         import pyangbind
         print("Using dir {}/{} for python artifacts".format(os.getcwd(), self.im_dir))
         path = "{}/{}".format(os.getcwd(), self.im_dir)