Updated User Agent & More Samples for Billing Plans

- Fixed versioning in User Agent.
- Updated Billing Plan sample to update Payment definitions
- Docs & Tests

sample/doc/payments/AuthorizationCapture.html

@@ -14,7 +14,7 @@ with a valid ApiContext (See bootstrap.php for more on <code>ApiContext</code>)<
 
     <span class="hljs-variable">$amt</span> = <span class="hljs-keyword">new</span> Amount();
     <span class="hljs-variable">$amt</span>-&gt;setCurrency(<span class="hljs-string">"USD"</span>)
-        -&gt;setTotal(<span class="hljs-string">"1.00"</span>);
+        -&gt;setTotal(<span class="hljs-number">1</span>);
 
     <span class="hljs-comment">### Capture</span>
     <span class="hljs-variable">$capture</span> = <span class="hljs-keyword">new</span> Capture();