Deprecate the original RC interface in Selenium.

As part of Selenium 3.0, we shall be moving the original RC interface to a
legacy JAR that will be available as a separate download. As the first step
in this process, the original "Selenium" interface is being marked as
deprecated.

java/client/src/com/thoughtworks/selenium/Selenium.java

@@ -159,7 +159,9 @@
  * are backslash-escaped. When providing a pattern, the optional matching syntax (i.e. glob, regexp,
  * etc.) is specified once, as usual, at the beginning of the pattern.
  * </p>
+ * @deprecated The RC interface will be removed in Selenium 3.0. Please migrate to using WebDriver.
  */
+@Deprecated
 public interface Selenium {
 
   /** Sets the per-session extension Javascript */