Add Codestyle project to Forge Core

Add a Codestyle project to the Forge Core repository.
The Codestyle project should hold

1. Maven plugin configuration (Checkstyle or PMD or Findbugs, for example)
2. IDE codestyle configuration (for Eclipse, IntelliJ IDEA and optionally others)
3. License texts (for use by licence plugins) if necessary
4. Maven Enforcer rules

A similar example of a Codestyle project can be seen in the Codestyle project
found under the documentation link in https://bitbucket.org/lennartj/nazgul_tools/wiki/Home