Add Ant build instructions and github CI.

[hopskipnfall]

• For each commit on master, as well as all PRs to master Github will test that the server builds.
• Adds build instructions requested in #4
• Fixes a few issues in build.xml and src/org/emulinker/kaillera/controller/v086/protocol/V086Message.java
• Adds build/.gitignore which guarantees that the build/ directory exists so Ant won't complain.

There are a few other changes that are already present in the main repository... i'm not sure how to make them not appear here.