Change multibag repository reference to master branch

Author: Shunichi Shinohara

rebar.config

@@ -54,5 +54,5 @@
 
 {deps_ee, [
            {riak_repl_pb_api,".*",{git,"git@github.com:basho/riak_repl_pb_api.git", {tag, "0.2.5"}}},
-           {riak_cs_multibag,".*",{git,"git@github.com:basho/riak_cs_multibag.git", {tag, "1.5.0"}}}
+           {riak_cs_multibag,".*",{git,"git@github.com:basho/riak_cs_multibag.git", {tag, "1.5.2"}}}
           ]}.