Added support for Coveralls.io

Coveralls.io is a free code coverage tool that can be run after Travis
CI has finished a build.  This will be a great tool to track JUnit test
code coverage.
Make Travis CI run JaCoCo and notify Coveralls
Updated JaCoCo plugin to the newest version

The 0.6.4 version of the jacoco-maven-plugin broke when running with
Java 8.  The new version, 0.7.1, supposedly does not so we are updating.
Merge pull request #49 from bnorm-software/coveralls

Coveralls