Apparently there's this neat thing called JitPack that makes a public maven repo for public Github repos on the fly. According to it, this is all you need to do to add this to your maven project:
<repositories>
<repository>
<id>jitpack.io</id>
<url>https://jitpack.io</url>
</repository>
</repositories>
Replace <version>
number with this number:
<dependency>
<groupId>com.github.TechFortress</groupId>
<artifactId>GriefPrevention</artifactId>
<version>16.4</version>
</dependency>
You can also add it to gradle/sbt/leiningen projects: https://jitpack.io/#TechFortress/GriefPrevention/