Decimals break parameters rendering
**Describe the bug**
Providing a custom parameter of type `Number` with a floating point value (like 0.5) will break the regex mechanism of rendering templates.

**To Reproduce**
Provide a floating point numeric parameter.

**Expected behavior**
Parameter expansion to work normally.

**Version**
 - Taskcat Version 0.9.0
-  Python Version 3.6.5
diff --git a/taskcat/_template_params.py b/taskcat/_template_params.py
index a4a5d0d..c091cd6 100644
--- a/taskcat/_template_params.py
+++ b/taskcat/_template_params.py
@@ -224,7 +224,7 @@ class ParamGen:
         Converts a parameter value to string
         No parameters. Operates on (ClassInstance).param_value
         """
-        if isinstance(self.param_value, (int, bytes)):
+        if isinstance(self.param_value, (int, float, bytes)):
             self.param_value = str(self.param_value)
 
     @staticmethod
['taskcat/_template_params.py']