Update Guava to 19.0-RC2 to match Guava version in Gerrit core

Change-Id: I86ce5e28045c53e4191e9ac828e9793e5760e406
Signed-off-by: Edwin Kempin <ekempin@google.com>

lib/BUCK

diff --git a/lib/BUCK b/lib/BUCK
index 1b47c6c..9c596fa 100644
--- a/lib/BUCK
+++ b/lib/BUCK
@@ -2,8 +2,8 @@
 
 maven_jar(
   name = 'guava',
-  id = 'com.google.guava:guava:19.0-rc1',
-  sha1 = '0364538ac107b8943a1f4d68ac50f1b0421bb983',
+  id = 'com.google.guava:guava:19.0-rc2',
+  sha1 = '93e17f60bc524c2610b41c494bb829c11ca89436',
   license = 'Apache2.0',
 )