Merge pull request #79 from pkohout-profitsee/master

fixed nullpointer exception in OAuthAccessToken.

Author: SidneyAllen

src/main/java/com/xero/api/OAuthAccessToken.java

@@ -58,7 +58,7 @@ public OAuthAccessToken build(String verifier, String tempToken, String tempToke
   }
 
   public OAuthAccessToken build() throws IOException {
-    
+    httpclient = new XeroHttpContext(config).getHttpClient();
     return this;
   }