Fixed bug in 'oe' script when passing no arguments

When no arguments passed to 'oe' script next exception was thrown:

```
Traceback (most recent call last):
  File "./oe", line 5, in <module>
    if sys.argv[1] == 'run-tests':
IndexError: list index out of range
```

oe

@@ -2,7 +2,7 @@
 
 if __name__ == '__main__':
     import sys
-    if sys.argv[1] == 'run-tests':
+    if len(sys.argv) > 1 and sys.argv[1] == 'run-tests':
         sys.exit(0)
     import openerpcommand.main
     openerpcommand.main.run()