Add option to set the path of the dbca template

[talek]

Currently dbca_templatename can't refer to a file outside of the ./templates sub-directory. This is a problem if you maintain a location with various dbca template files, outside of the role/playbook structure. So, it should be possible to provide the source path of the dbca template as well. I know that you can set dbca_copy_template to false and copy the template file yourself, but I feel that oradb_manage_db role should be smart enough to handle this simple scenario by its own. Another way to address this would be to specify the full path as part of the dbca_templatename property and apply a basename filter here and there, but I think it is more complicated and it doesn't pay off the trouble.

[Rendanic]

Great idea, looks fine for me.