util: in-memory storage

refs #1940

specification:
http://redmine.named-data.net/projects/ndn-cxx/wiki/InMemoryStorage

Change-Id: I7416d0dac4b4865ad931c3bf83180a043788405b
diff --git a/AUTHORS.md b/AUTHORS.md
index 504d492..1238782 100644
--- a/AUTHORS.md
+++ b/AUTHORS.md
@@ -26,3 +26,4 @@
 * Lixia Zhang           <http://www.cs.ucla.edu/~lixia/home.html>
 * Jeff Burke            <http://remap.ucla.edu/jburke/>
 * Xiaoke Jiang          <http://netarchlab.tsinghua.edu.cn/~shock/>
+* Jiewen Tan            <alanwake@ucla.edu>