[REEF-1811] Move current bridge Avro messages to lang/common/bridge/avro

  - Move the current avro messages on the java side to
    lang/common/bridge/avro so both the C# and java
    sides can generate compatible messages classes from
    the common avsc files.

JIRA:
  [REEF-1811](https://issues.apache.org/jira/browse/REEF-1811)

Pull Request:
  This closes #1315
diff --git a/lang/java/reef-bridge-java/src/main/avro/Bridge.avsc b/lang/common/bridge/avro/Bridge.avsc
similarity index 100%
rename from lang/java/reef-bridge-java/src/main/avro/Bridge.avsc
rename to lang/common/bridge/avro/Bridge.avsc
diff --git a/lang/java/reef-bridge-java/src/main/avro/DefinedRuntimes.avsc b/lang/common/bridge/avro/DefinedRuntimes.avsc
similarity index 100%
rename from lang/java/reef-bridge-java/src/main/avro/DefinedRuntimes.avsc
rename to lang/common/bridge/avro/DefinedRuntimes.avsc
diff --git a/lang/java/reef-bridge-java/pom.xml b/lang/java/reef-bridge-java/pom.xml
index a34715e..6d6ff2a 100644
--- a/lang/java/reef-bridge-java/pom.xml
+++ b/lang/java/reef-bridge-java/pom.xml
@@ -100,7 +100,7 @@
                             <goal>schema</goal>
                         </goals>
                         <configuration>
-                            <sourceDirectory>${project.basedir}/src/main/avro/</sourceDirectory>
+                            <sourceDirectory>${rootPath}/lang/common/bridge/avro/</sourceDirectory>
                             <outputDirectory>${project.basedir}/target/generated-sources/avro/</outputDirectory>
                         </configuration>
                     </execution>