Remove Unused Scheduler.parallelism

Before hitting 1.0 removing this API as it is not used.

Author: benjchristensen

src/main/java/rx/Scheduler.java

@@ -135,18 +135,6 @@ public long now() {
         }
     }
 
-    /**
-     * Indicates the parallelism available to this Scheduler.
-     * <p>
-     * This defaults to {@code Runtime.getRuntime().availableProcessors()} but can be overridden for use cases
-     * such as scheduling work on a computer cluster.
-     * 
-     * @return the scheduler's available degree of parallelism
-     */
-    public int parallelism() {
-        return Runtime.getRuntime().availableProcessors();
-    }
-
     /**
      * Gets the current time, in milliseconds, according to this Scheduler.
      *