Adding hello world API docs and updating returnSizes mentions.

documentation/api/GetHelloWorld.markdown

@@ -0,0 +1,87 @@
+Open Photo API / Hello World
+=======================
+#### OpenPhoto, a photo service for the masses
+
+----------------------------------------
+
+1. [Purpose][purpose]
+1. [Endpoint][endpoint]
+1. [Parameters][parameters]
+1. [Examples][examples]
+  * [Curl][example-curl]
+  * [PHP][example-php]
+1. [Response][response]
+  * [Sample][sample]
+
+----------------------------------------
+
+<a name="purpose"></a>
+### Purpose of the Get Hello World API
+
+This endpoint is used to test connectivity and/or authentication. Any parameters passed in the query string are returned in the response.
+
+----------------------------------------
+
+<a name="endpoint"></a>
+### Endpoint
+
+_Authentication: optional_
+
+    GET /hello.json
+
+<a name="parameters"></a>
+### Parameters
+
+1.  auth (optional), Pass this in with a value of `true` to test OAuth requests.
+
+----------------------------------------
+
+<a name="examples"></a>
+### Examples
+
+<a name="example-curl"></a>
+#### Command line curl
+
+    curl "http://jmathai.openphoto.me/hello.json"
+    curl "http://jmathai.openphoto.me/hello.json?auth=true"
+
+<a name="example-php"></a>
+#### PHP
+
+    $ch = curl_init('http://jmathai.openphoto.me/hello.json');
+    curl_exec($ch);
+
+----------------------------------------
+
+<a name="response"></a>
+### Response
+
+The response is in a standard [response envelope][Envelope].
+
+* _message_, A string describing the result. Don't use this for anything but reading.
+* _code_, _200_ on success
+* _result_, An array of [Tag][Tag] objects
+
+<a name="sample"></a>
+#### Sample
+
+    {
+      "message":"Hello, world!",
+      "code":200,
+      "result":
+      {
+        "__route__":"\/hello.json"
+      }
+    }
+
+[Envelope]: api/Envelope.markdown
+[purpose]: #purpose
+[endpoint]: #endpoint
+[parameters]: #parameters
+[examples]: #examples
+[example-curl]: #example-curl
+[example-php]: #example-php
+[response]: #response
+[sample]: #sample
+
+