Fixes #225 - Use a properly defined user agent

* Set a proper user agent
* Add fallback when UA comes out nil
* Remove unused Bundle extension
* Return nil when asciification fails
* Add whitespace handling and further emoji test case
* Explicitly check if string is already in ASCII
* Rename factory to builder
* Use allSatisfy instead of reduce
* Use key path syntax

ElementX.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -9,6 +9,15 @@
         "version" : "1.5.0"
       }
     },
+    {
+      "identity" : "devicekit",
+      "kind" : "remoteSourceControl",
+      "location" : "https://github.com/devicekit/DeviceKit",
+      "state" : {
+        "revision" : "20e0991f3975916ab0f6d58db84d8bc64f883537",
+        "version" : "4.7.0"
+      }
+    },
     {
       "identity" : "dtcoretext",
       "kind" : "remoteSourceControl",