Build System: Enable python3 compatibility.

* Consistently use spaces in rest-api-templates/asterisk_processor.py.
* Exclude third-party from docs/full-en_US.xml.
* Add docs/full-en_US.xml to .gitignore.
* Use list() to convert python3 view.
* Use python3 print function.
* Replace cmp() with equivalent equation.
* Replace reference to out of scope subtype variable with name
  parameter.
* Use unescaping triple bracket notation in mustache templates where
  needed.  This causes behavior of Python2 to be maintained when using
  Python3.
* Fix references to has_websocket / is_websocket in
  res_ari_resource.c.mustache.
* Update calculation of has_websocket to use any().
* Use unicode mode for writing output file in transform.py.
* Replace 'from swagger_model import *' with explicit import of required
  symbols.
* Add missing 'import os'
* Fix invalid reference to swagger_version from exception handler.

I have not tested voicemailpwcheck.py, only the print syntax has
been fixed.

Change-Id: If5c5b556a2800d41a3e2cfef080ac2e151178c33

rest-api-templates/transform.py

@@ -21,6 +21,11 @@ import os.path
 import pystache
 import shutil
 import tempfile
+import sys
+
+if sys.version_info[0] == 3:
+    def unicode(v):
+        return str(v)
 
 
 class Transform(object):
@@ -52,11 +57,10 @@ class Transform(object):
         dest_exists = os.path.exists(dest_file)
         if dest_exists and not self.overwrite:
             return
-        tmp_file = tempfile.mkstemp()
-        with tempfile.NamedTemporaryFile() as out:
+        with tempfile.NamedTemporaryFile(mode='w+') as out:
             out.write(renderer.render(self.template, model))
             out.flush()
 
             if not dest_exists or not filecmp.cmp(out.name, dest_file):
-                print "Writing %s" % dest_file
+                print("Writing %s" % dest_file)
                 shutil.copyfile(out.name, dest_file)