Update Travis CI configuration (#3521)
Update Travis CI configuration (#3521)

* Run on Ubuntu Bionic 18.04
* Remove OpenJDK 14 from build matrix
* Only build specific branches and tags
dropwizard/dropwizard,Alexey1Gavrilov/dropwizard,phambryan/dropwizard,micsta/dropwizard,micsta/dropwizard,Alexey1Gavrilov/dropwizard,micsta/dropwizard,phambryan/dropwizard,dropwizard/dropwizard,Alexey1Gavrilov/dropwizard,dropwizard/dropwizard,phambryan/dropwizard