Add JimFS to Bazel's third_party

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MOS_MIGRATED_REVID=114242270

third_party/README.md

diff --git a/third_party/README.md b/third_party/README.md
index d6aec2d..7e72f70 100644
--- a/third_party/README.md
+++ b/third_party/README.md
@@ -183,6 +183,12 @@
 * License: Eclipse Distribution License 1.0
 
 
+## [JimFS](https://github.com/google/jimfs)
+
+* Version: 1.1-rc1
+* License: Apache License 2.0
+
+
 ## [joda_time](http://www.joda.org/joda-time/)
 
 * Version: 2.3