Remove filter for license

We have the context function which can be used with:

{{ license('Apache-2.0') }}

and this function is already used in all templates. So remove
the "old-style" license handling.

Change-Id: Ia7f1cc0ec004696949f36b86f982f76ad358871e

doc/source/usage.rst

@@ -148,12 +148,12 @@ With an existing yaml (and `oslo.config` epoch set to 2), this would be rendered
   Epoch: 2
 
 
-context filter `license`
+context function `license`
 ************************
 The templates use `SPDX`_ license names and theses names are translated for different distros.
 For example, a project uses the `Apache-2.0` license::
 
-  License: {{ 'Apache-2.0' | license }}
+  License: {{ license('Apache-2.0') }}
 
 With the `fedora` spec-style, this would be rendered to::
 

renderspec/__init__.py

@@ -102,11 +102,6 @@ def _context_license_spdx(context, value):
 ###############
 # jinja2 filter
 ###############
-@contextfilter
-def _filter_license_spdx(context, value):
-    return _context_license_spdx(context, value)
-
-
 @contextfilter
 def _filter_epoch(context, value):
     return _context_epoch(context, value)
@@ -137,7 +132,6 @@ def _globals_py2name(context, value):
 
 def _env_register_filters_and_globals(env):
     """register all the jinja2 filters we want in the environment"""
-    env.filters['license'] = _filter_license_spdx
     env.filters['epoch'] = _filter_epoch
     env.globals['py2pkg'] = _globals_py2pkg
     env.globals['py2name'] = _globals_py2name