Fix misspellings in heat

Fix misspellings detected by:
* pip install misspellings
* git ls-files | grep -v locale | misspellings -f -

Change-Id: I554143f00fe82154472e7eb6391291730dd3ddd4
Closes-Bug: #1257295
Closes-Bug: #1277515
Remove TODO comments in create_resource

Since it's XML handling related and the ever having XML API intention
has been removed.

Change-Id: I7d7328f6d13caa861b7fc4b3fd22c4450b6097e5
Merge "Fix misspellings in heat"
Merge "Remove TODO comments in create_resource"