Support for Hikari connection pool - HikariCpPooledDataSourceCreator

Here is a DataSourceCreator for the Hikari connection pool. I based it off the existing `BasicDbcpPooledDataSourceCreator`, note that some of the properties in the Hikari pool are not the same as in the commons-pool derived projects. For example, `jdbcUrl` vs `url` and `maximumPoolSize` vs `maxPoolSize`.

I hope you will accept this PR, please let me know if there is anything necessary to get this merged, its a real pain to manage a custom version of a spring library. :)

Thanks.