Update build process

[sam]

Since the pom.xml is required for bootstrapping, let's just remove the bootstrapping code within Doubleshot. It's a bit difficult to maintain, and the project will integrate better with other tools without attempting to bootstrap itself.

Instead we'll just move the Java build process to the pom.xml. Hopefully this will also address the flakyness with TravisCI builds It's hit or miss wether it's able to download all JAR dependencies in a single pass since the environment is entirely empty with nothing in it's local repository. There's rarely anything actually failing in the code, but because of this the builds fail on TravisCI about half the time on at least one of the three JDK versions it's tested against.