Added comments for the feature maintainer.
Use /dev/urandom for more secure session id generation.
More better session id generation(2bit).
suggested by @kazuho++
Cache file handle for /dev/urandom.

Suggested by @kazuho++
Refactoring.
Oops. I forgot to rewrite test case.
Merge branch 'urandom'
Checking in changes prior to tagging of version 1.02.

Changelog diff is:

diff --git Changes Changes
index a54cf21..9d6e244 100644
--- Changes
+++ Changes
@@ -2,6 +2,10 @@ Revision history for Perl extension HTTP-Session2

 {{$NEXT}}

+1.02 2014-07-31T21:14:50Z
+
+    - Better session id generation using /dev/urandom.
+
 1.01 2014-07-28T11:43:10Z

     - Revert HMAC strategy...