Buck Plugin: Reverting guava version to 19.0

Buck uses guava 19.0, so the plugin needs to be built against that version

Change-Id: I66e9eda7e90cb4f001c523231281b6a041c0f6e5
diff --git a/tools/build/buck-plugin/BUCK b/tools/build/buck-plugin/BUCK
index b66e0cd..8593941 100644
--- a/tools/build/buck-plugin/BUCK
+++ b/tools/build/buck-plugin/BUCK
@@ -13,9 +13,18 @@
 #  binary_jar = 'lib/buck.jar'
 # )
 
+# Use buck's guava version - 19.0
+remote_jar (
+  name = 'guava',
+  out = 'guava-19.0.jar',
+  url = 'mvn:com.google.guava:guava:jar:19.0',
+  sha1 = '6ce200f6b23222af3d8abb6b6459e6c44f4bb0e9',
+  maven_coords = 'com.google.guava:guava:19.0',
+)
+
 COMPILE = [
   '//lib:qdox',
-  '//lib:guava',
+  ':guava',
   '//lib:bndlib',
   '//lib:org.apache.felix.scr.bnd'
 ]