Add support for Java 9 Modules

[jamesdbaker]

Add a module-info.java file to the library so that it is compatible with Java 9+. Specifically, doing so will avoid the following warning when including Iban4J in a Java 9 project:

[WARNING] ********************************************************************************************************************
[WARNING] * Required filename-based automodules detected. Please don't publish this project to a public artifact repository! *
[WARNING] ********************************************************************************************************************

[jamesdbaker]

Alternatively, could add an entry to the manifest to at least declare the module name