Get better format for long lines with PrettyTable

Based on current implement, the cli output format will be bad if
the lines are too long. This issue can be fixed by setting 'max_width'.
However, there is a bug against it, see
https://code.google.com/p/prettytable/source/browse/trunk/CHANGELOG?r=85
line 3. So the requirements.txt is updated as well.

Fixes bug 1251283

Change-Id: Id22bc929fa8cb89941d385308e333b7359ff7118

global-requirements.txt

@@ -49,7 +49,7 @@ PasteDeploy>=1.5.0
 pbr>=0.5.21,<1.0
 pecan>=0.2.0
 pip>=1.4
-PrettyTable>=0.6,<0.8
+PrettyTable>=0.7,<0.8
 psutil>=0.6.1,<1.0
 pyasn1
 pycadf>=0.1.9