Fix configuration of mycila license plugin

In OpenMRS core, the license plugin was only defined in the top-level pom.  This was causing two issues:

• Any child projects that had their own plugin configuration were not running the license check (I believe, not 100% sure about this)
• For child projects that did not have their own plugin configuration, the license check was being run, but the header file was referenced via a relative path and so would fail if attempting to build the project from anywhere but the top-level openmrs-core directory (which happens often when running via the SDK)

To fix, I:

• Moved the mycila configuration into dependency management
• Explicitly configured the plugin to run in each pom and reference the proper path to the license file