SignatureCalculator should be resolved before computing the final URI, close AsyncHttpClient#739

Author: Stephane Landelle

api/src/main/java/org/asynchttpclient/RequestBuilderBase.java

@@ -607,8 +607,8 @@ private void computeFinalUri() {
     }
 
     public Request build() {
-        computeFinalUri();
         executeSignatureCalculator();
+        computeFinalUri();
         computeRequestCharset();
         computeRequestLength();
         return request;