Update maven-compiler-plugin to 3.6.1
Update maven-compiler-plugin to 3.6.1

Closes #304.

kneubi/fscrawler,dadoonet/fsriver,kneubi/fscrawler,kneubi/fscrawler,dadoonet/fscrawler,dadoonet/fsriver,dadoonet/fscrawler,dadoonet/fsriver,dadoonet/fscrawler