Allow per-Operation docstrings

Previously, GET and POST requests both used the same description, which
doesn't make sense when they do different things.  I've changed this to
use` __doc__` or `description` attributes
 on the `get` or `post` method if available.

src/labthings/apispec/plugins.py

@@ -60,14 +60,19 @@ def spec_for_interaction(cls, interaction):
 
         for method in http_method_funcs:
             if hasattr(interaction, method):
+                property = getattr(interaction, method)
                 d[method] = {
-                    "description": getattr(interaction, "description", None)
-                    or get_docstring(interaction),
-                    "summary": getattr(interaction, "summary", None)
+                    "description": getattr(property, "description", None)
+                    or get_docstring(property, remove_newlines=False)
+                    or getattr(interaction, "description", None)
+                    or get_docstring(interaction, remove_newlines=False),
+                    "summary": getattr(property, "summary", None)
+                    or get_summary(property)
+                    or getattr(interaction, "summary", None)
                     or get_summary(interaction),
                     "tags": list(interaction.get_tags()),
                     "responses": {
-                        "default": {
+                        "5XX": {
                             "description": "Unexpected error",
                             "content": {
                                 "application/json": {