SPARK-2414 [BUILD] Add LICENSE entry for jquery

The JIRA concerned removing jquery, and this does not remove jquery. While it is distributed by Spark it should have an accompanying line in LICENSE, very technically, as per http://www.apache.org/dev/licensing-howto.html

Author: Sean Owen <srowen@gmail.com>

Closes apache#1748 from srowen/SPARK-2414 and squashes the following commits:

2fdb03c [Sean Owen] Add LICENSE entry for jquery

LICENSE

@@ -549,3 +549,4 @@ The following components are provided under the MIT License. See project link fo
      (MIT License) pyrolite (org.spark-project:pyrolite:2.0.1 - http://pythonhosted.org/Pyro4/)
      (MIT License) scopt (com.github.scopt:scopt_2.10:3.2.0 - https://github.com/scopt/scopt)
      (The MIT License) Mockito (org.mockito:mockito-all:1.8.5 - http://www.mockito.org)
+     (MIT License) jquery (https://jquery.org/license/)