Remove prettytable pin to 0.5

* The clients have all been fixed to work with prettytable 0.6

Change-Id: I968d73862e6d45d6974c43ea47ba84e8210ed787
diff --git a/files/pips/general b/files/pips/general
index f740306..deb2d14 100644
--- a/files/pips/general
+++ b/files/pips/general
@@ -1 +1 @@
-prettytable==0.5
+prettytable