Fix Terracotta-OSS#20: Expose new methods through IClientTestEnvironment

-getNumberOfStripes() and getNumberOfServersPerStripe()
-note that most users of this class don't support creating multi-stripe test environments

test-interfaces/src/main/java/org/terracotta/passthrough/IClientTestEnvironment.java

@@ -42,4 +42,14 @@ public interface IClientTestEnvironment {
    * @return {@link IClusterInfo} which provides information about connecting cluster
    */
   public IClusterInfo getClusterInfo();
+
+  /**
+   * @return The number of stripes in the current environment (always > 0).
+   */
+  public int getNumberOfStripes();
+
+  /**
+   * @return The number of servers within a given stripe in the current environment (always > 0).
+   */
+  public int getNumberOfServersPerStripe();
 }