Add numpad key mappings to Selenium WebDriver Keys

according to the standard https://w3c.github.io/webdriver/#keyboard-actions

Author: iampopovich

rb/lib/selenium/webdriver/common/keys.rb

@@ -75,6 +75,13 @@ module Keys
         subtract: "\ue027",
         decimal: "\ue028",
         divide: "\ue029",
+        numpad_multiply: "\ue024",
+        numpad_add: "\ue025",
+        numpad_comma: "\ue026",
+        numpad_subtract: "\ue027",
+        numpad_decimal: "\ue028",
+        numpad_divide: "\ue029",
+        numpad_enter: "\ue007",
         f1: "\ue031",
         f2: "\ue032",
         f3: "\ue033",