Added jasmine.isSpy to the public interface

* Fixes #1880

lib/jasmine-core/jasmine.js

@@ -512,6 +512,14 @@ getJasmineRequireObj().base = function(j$, jasmineGlobal) {
     return new j$.SetContaining(sample);
   };
 
+  /**
+   * Determines whether the provided function is a Jasmine spy.
+   * @name jasmine.isSpy
+   * @since 2.0.0
+   * @function
+   * @param {Function} putativeSpy - The function to check.
+   * @return {Boolean}
+   */
   j$.isSpy = function(putativeSpy) {
     if (!putativeSpy) {
       return false;

src/core/base.js

@@ -344,6 +344,14 @@ getJasmineRequireObj().base = function(j$, jasmineGlobal) {
     return new j$.SetContaining(sample);
   };
 
+  /**
+   * Determines whether the provided function is a Jasmine spy.
+   * @name jasmine.isSpy
+   * @since 2.0.0
+   * @function
+   * @param {Function} putativeSpy - The function to check.
+   * @return {Boolean}
+   */
   j$.isSpy = function(putativeSpy) {
     if (!putativeSpy) {
       return false;