Fixing small bug in iptest. Can now be run as "iptest".

IPython/testing/iptest.py

@@ -287,6 +287,9 b' def run_iptestall():'
 
 
 def main():
+    if len(sys.argv) == 1:
+        run_iptestall()
+    else:
     if sys.argv[1] == 'all':
         run_iptestall()
     else: