Create configuration schemas for statistics module

Assigning for review.

• Needs to be moved to the /schema folder
• Use single quotes instead of double quotes (ref Code style to use for schema files).
• Improve the line of documentation at the top. eg "# Schema for the configuration files of the statistics module."

Keeping this assigned to me for the moment, I'm going to address these issues right away.

Removed - double post.

Addressed remarks from #15.

@guy-schneerson just pointed out to me that the configuration keys should not be quoted. Updated patch.

I've never reviewed any config schemas before, so please take this with a grain of salt - I may be totally off base with my comments here. :-)

+    block:
+      type: mapping
+      label: 'Block settings'
+      mapping:
+        popular:
+          type: mapping
+          label: 'Popular Block'

Drupal usually uses sentence case, rather than title case, so this should be 'Popular block' with a lower-case 'b'.

However, on the block admin form, the block is actually called "Popular content". So, I'd like to propose that this label actually be 'Popular content' or 'Popular content block'.

+          mapping:
+            top_day_limit:
+              type: integer
+              label: 'Top day limit'

On the block configure form, this is actually: "Number of day's top views to display" - why not make it match?

+            top_all_limit:
+              type: integer
+              label: 'Top all limit'

On the block configure form, this is actually: "Number of all time views to display"

+            top_recent_limit:
+              type: integer
+              label: 'Top recent limit'

On the block configure form, this is actually: "Number of most recent views to display"

I posted a comment on #1910624: [META] Introduce and complete configuration schemas in all of core asking if we really need to worry about the labels matching the admin form. You can wait until I get feedback there to actually update your patch. If they say this doesn't matter, I'll come back and mark this as RTBC.

I got clarification from YesCT that the labels should match the admin form labels and I've attached a new patch which addresses this.

+++ b/core/modules/statistics/config/schema/statistics.schema.yml
@@ -0,0 +1,36 @@
+              label: 'Number of day''s top views to display'

I think this should be "Number of day's top views to display"

I don't see the difference. :-/ Or are you referring to the double single quote ('')? That's how you escape single quotes in a YAML file.

I'm going to mark this back to "needs review" under the assumption that the double single quote threw you off. If it's something else, please post another comment and mark as "needs work" again.

Thanks for the review!

Committed to 8.x, thanks! I'll push once testbot has caught up a bit.

Re #22: Yes that totally threw me off. I didn't know that's how YAML works. Looks weird, but hey. Sorry for the noise.