Allow deploying main class with sbt-assembly

After this commit, you'll be able to run the tests successfully (at
least on 2.10.4, OS X 10.9, and Java 7) with:

```
$ sbt "project los-eval" assembly
$ java -jar eval/target/los-eval-assembly-0.1-SNAPSHOT.jar \
src/test/resources/Bugs.zip
```

This suggests that the problem is either running under SBT, or some
classpath-related issue (which might arise because Travis uses Paul
Phillips SBT runner, unlike me). Note: I use Brew's SBT runner and have
troubles; everything works fine on Jenkins on Linux (with Jenkins SBT
runner), and I should test again on the Linux servers I used for
development when I used to work on SQuOpt.

The used JDK version might also be relevant, who knows?