Fix issues with CLI introduced by up-rev of cmd2 module from 0.6.9
to 0.7.0.

Change-Id: I5c1badb856c43331c68c7979e4b0a006c449ae20
diff --git a/requirements.txt b/requirements.txt
index 4eab93f..054d32e 100755
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,6 @@
 argparse==1.2.1
 arrow>=0.10.0
-cmd2>=0.6.9
+cmd2==0.7.0
 colorama>=0.2.5
 cython==0.24.1
 decorator>=3.4.0