openbmctool: drop simplejson

The simplejson module was never used directly by the script and the
problem it's inclusion was working around has been fixed, so remove.

Change-Id: I6e2ab12233ab83351276920a953e454aa40785c1
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/thalerj/openbmctool.py b/thalerj/openbmctool.py
index c2c8fe4..7d702b6 100755
--- a/thalerj/openbmctool.py
+++ b/thalerj/openbmctool.py
@@ -16,7 +16,6 @@
 """
 import argparse
 import requests
-import simplejson
 import getpass
 import json
 import os