Update to SLF4j 1.7.7
Merged #122 "Update to SLF4j 1.7.7"
Update to gson 2.2.2
Update to Freemarker 2.3.20
Merged #123 "Update to gson 2.2.2"
Merged #124 "Update to Freemarker 2.3.20"
Refine startup ascii artwork