The silver searcher: new version (#5630)

* Updating ag to the latest version

* Pretty by request

* Restore url to previous value

There *is* an https version available, but I've also been told
to not just update the url when adding new version.  I'm following
the latter advice and trusting security to the digest.

var/spack/repos/builtin/packages/the-silver-searcher/package.py

@@ -27,9 +27,11 @@
 
 class TheSilverSearcher(AutotoolsPackage):
     """Fast recursive grep alternative"""
+
     homepage = "http://geoff.greer.fm/ag/"
     url      = "http://geoff.greer.fm/ag/releases/the_silver_searcher-0.32.0.tar.gz"
 
+    version('2.1.0', '3e7207b060424174323236932bf76ec2')
     version('0.32.0', '3fdfd5836924246073d5344257a06823')
     version('0.30.0', '95e2e7859fab1156c835aff7413481db')