Added carriage returns (\r) to lines written to DDL file.

DDL generated by Ebean uses \r\n. This patch makes Play also use \r\n so the file will have consistent line endings.
More details at https://groups.google.com/forum/#!topic/play-framework/-H0MgRPFd60

Review by @jroper
Backport to 2.0.x
Merge pull request #766 from stianl/ddl-line-endings

Added carriage returns (\r) to lines written to DDL file.