Add new package: shiro (#18541)

* Add new package: shiro

* refine description and dependencies

var/spack/repos/builtin/packages/shiro/package.py

+# Copyright 2013-2020 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class Shiro(MavenPackage):
+    """Apache Shiro is a powerful and easy-to-use Java security framework
+    that performs authentication, authorization, cryptography, and session
+    management. With Shiro's easy-to-understand API, you can quickly and
+    easily secure any application - from the smallest mobile applications
+    to the largest web and enterprise applications."""
+
+    homepage = "https://shiro.apache.org/"
+    url      = "https://github.com/apache/shiro/archive/shiro-root-1.6.0.tar.gz"
+
+    version('1.6.0', sha256='50338badfd3261076060fbe70330089512d38071bc51aa3f84ad23e707d2b7c9')
+    version('1.5.3', sha256='25c5d99eddf790969e0f80bd9769f773465c9c9e1e8ec1f549f476bdae8c6983')
+
+    depends_on('java@8:', type=('build', 'run'))
+    depends_on('maven@3.5:3.999', type='build')