Fixed superfluous ampersand when queries are embedded in paths

lib/httparty/request.rb

@@ -174,6 +174,7 @@ def query_string(uri)
         query_string_parts << options[:query] unless options[:query].nil?
       end
 
+      query_string_parts.reject!(&:empty?) unless query_string_parts == [""]
       query_string_parts.size > 0 ? query_string_parts.join('&') : nil
     end
 

spec/httparty/request_spec.rb

@@ -133,6 +133,12 @@
         URI.unescape(@request.uri.query).should == ""
       end
 
+      it "does not append an ampersand when queries are embedded in paths" do
+        @request.path = "/path?a=1"
+        @request.options[:query] = {}
+        @request.uri.query.should == "a=1"
+      end
+
       it "does not duplicate query string parameters when uri is called twice" do
         @request.options[:query] = {:foo => :bar}
         @request.uri