Upgrade Flogger to version 0.4

The few additions and updates brought by this version are listed in [1].

[1] https://github.com/google/flogger/releases/tag/flogger-0.4

Change-Id: I8ad0c8d662344424c87b073052493373182a4a28
diff --git a/WORKSPACE b/WORKSPACE
index 47ead15d..10ee2c9 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -212,18 +212,18 @@
     sha1 = "94ad16d728b374d65bd897625f3fbb3da223a2b6",
 )
 
-FLOGGER_VERS = "0.3.1"
+FLOGGER_VERS = "0.4"
 
 maven_jar(
     name = "flogger",
     artifact = "com.google.flogger:flogger:" + FLOGGER_VERS,
-    sha1 = "585030fe1ec709760cbef997a459729fb965df0e",
+    sha1 = "9c8863dcc913b56291c0c88e6d4ca9715b43df98",
 )
 
 maven_jar(
     name = "flogger-log4j-backend",
     artifact = "com.google.flogger:flogger-log4j-backend:" + FLOGGER_VERS,
-    sha1 = "d5085e3996bddc4b105d53b886190cc9a8811a9e",
+    sha1 = "17aa5e31daa1354187e14b6978597d630391c028",
 )
 
 maven_jar(