configure cmarkgfm to make cms pages more flexible (#2182)

* configure cmarkgfm to make cms pages more flexible

closes #2181

* move unsafe markdown to its own render selection

Author: ewdurbin

pages/models.py

@@ -21,6 +21,7 @@
 from markupfield.markup import DEFAULT_MARKUP_TYPES
 
 import cmarkgfm
+from cmarkgfm.cmark import Options as cmarkgfmOptions
 
 from cms.models import ContentManageable
 from fastly.utils import purge_url
@@ -29,6 +30,11 @@
 
 DEFAULT_MARKUP_TYPE = getattr(settings, 'DEFAULT_MARKUP_TYPE', 'restructuredtext')
 
+# Set options for cmarkgfm for "unsafe" renderer, see https://github.com/theacodes/cmarkgfm#advanced-usage
+CMARKGFM_UNSAFE_OPTIONS = (
+    cmarkgfmOptions.CMARK_OPT_UNSAFE
+)
+
 PAGE_PATH_RE = re.compile(r"""
     ^
     /?                      # We can optionally start with a /
@@ -59,6 +65,14 @@
     'Markdown'
 )
 
+RENDERERS.append(
+    (
+        "markdown_unsafe",
+        lambda markdown_text: cmarkgfm.github_flavored_markdown_to_html(markdown_text, options=CMARKGFM_UNSAFE_OPTIONS),
+        "Markdown (unsafe)",
+    )
+)
+
 
 class Page(ContentManageable):
     title = models.CharField(max_length=500)