Flyway support added to mifosx via Gradle

gradle tasks will now show new flyway commands. We used the gradle flyway plugin.

Run "gradle flywayInfo" to see the status of DB. Then you can run "gradle flywayMigrate" to migrate DB. Note: You must run this on a fresh database for the first time, so that flyway tables are created in DB. The SQL scripts that flyway runs are placed in the mifosng-db/migrations folder. They must follow V1, V2,... so on naming prefix to indicate which sequence and version each file must be run in.