Add support for OpenBSD, and also add some regression tests.

Add info about OpenBSD support to README.md and metadata.json
Add a note about OpenBSD java_version fact to README.markdown.
Fixup wording on context in one of the java patch level regression tests.
No mentioning of OpenBSD in metdata.json

Cleanup wording of context as suggested by @elyscape
update contexts as suggested by @elyscape

lib/facter/java_version.rb

@@ -18,3 +18,14 @@ Facter.add(:java_version) do
     end
   end
 end
+Facter.add(:java_version) do
+  confine :operatingsystem => 'OpenBSD'
+  has_weight 100
+  setcode do
+    Facter::Util::Resolution.with_env("PATH" => '/usr/local/jdk-1.7.0/jre/bin:/usr/local/jre-1.7.0/bin') do
+      if Facter::Util::Resolution.which('java')
+        Facter::Util::Resolution.exec('java -Xmx8m -version 2>&1').lines.first.split(/"/)[1].strip
+      end
+    end
+  end
+end