[examples/openspending] - openspending v0.2 (#907)

* [examples/openspending] - openspending v0.2

* [examples/openspending][m] - fix build

* [examples/openspending][xs] - fix build

* [examples/openspending][xs] - add prebuild step

* [examples/openspending][m] - fix requested by demenech

* [examples/openspending][sm] - remove links + fix bug

examples/openspending/content/help/conventions.md

@@ -0,0 +1,48 @@
+---
+section: help
+lead: true
+title: API conventions
+authors:
+- Neil Ashton
+redirect_from:
+- /help/api/
+---
+#### Authentication
+
+Some actions in OpenSpending require authentication, particularly those that write to the system or aim to access protected data (e.g. pre-publication datasets). For this purpose, each user is provided an API key. The key is displayed in the *settings* (go to the dashboard and click on *Change* next to the Information header). You can use it to perform authentication by adding the following into the HTTP headers (change <your-api-key> to the API key you find in your settings):
+
+    Authorization: ApiKey <your-api-key>
+
+#### JSON-P Callbacks
+
+All API calls that return JSON support JSON-P (JSON with padding). You can
+add a ``?callback=foo`` parameter to any query to wrap the output in a
+function call. This is used to include JSON data in other sites that do not
+support CORS:
+
+    $ curl http://openspending.org/cra.json?callback=foo
+
+    foo({
+        "description": "Data published by HM Treasury.",
+        "name": "cra",
+        "label": "Country Regional Analysis v2009",
+        "currency": "GBP"
+    });
+
+This can be used in remote web pages to include data as a simple ``script``
+tag:
+
+    <script>
+      function foo(data) {
+        alert(data.label);
+      }
+    </script>
+    <script src="http://openspending.org/cra.json?callback=foo"></script>
+
+<!--
+#### Cross Origin Resource Sharing
+
+The API does not yet support [CORS](http://code.google.com/p/html5security/wiki/CrossOriginRequestSecurity), but support will be added in the near future.
+-->
+
+**Up**: [OpenSpending API](../)