Strip any whitespace before checking for json

In case the template has any whitespace
we should strip it before checking if the
first character is a "{" to determine that its
a json template

Change-Id: Ia25444a2fde7019aa9fdf0d782599be78305ae9c
Closes-Bug: #1546166

heatclient/common/template_format.py

@@ -45,6 +45,8 @@ def parse(tmpl_str):
     This includes determination of whether the string is using the
     JSON or YAML format.
     """
+    # strip any whitespace before the check
+    tmpl_str = tmpl_str.strip()
     if tmpl_str.startswith('{'):
         tpl = json.loads(tmpl_str)
     else: