Fix avro conflict for hadoop1 and hadoop2.

Because avro is required by every module, this excludes it from other
dependencies to ensure the version is consistent. This also moves the
avro dependency _above_ the hive dependencies in the kite-data-hcatalog
pom because hive-exec includes avro classes (Schema) and is the cause of
a java.lang.VerifyError. Moving the dependency causes the constructed
classpath to search the avro jar first.