added pom_dwango.xml

added pom_dwango.xml for dwango scalastyle pom file.

you need to specify scala version with -P, by default 2.10.1 will used

#### build for scala 2.9.2
mvn -f pom_dwango.xml -P 2.9.2

#### build for scala 2.10.1
mvn -f pom_dwango.xml -P 2.10.1