Update to Chrome 53

Change-Id: I518b3f261adb633bb09a2597c9e7ee3cb6d63e6a

uitest/src/test/java/com/vaadin/tests/VerifyBrowserVersionTest.java

             // Chrome version does not necessarily match the desired version
             // because of auto updates...
             browserIdentifier = getExpectedUserAgentString(
-                    getDesiredCapabilities()) + "52";
+                    getDesiredCapabilities()) + "53";
         } else {
             browserIdentifier = getExpectedUserAgentString(desiredCapabilities)
                     + desiredCapabilities.getVersion();