Replace Cobertura with JaCoCo (#54)
Replace Cobertura with JaCoCo (#54)

Fixes: https://github.com/ProgrammingLife2016/PL2-2016/issues/51

Poses the impossibility to generate a aggregate report. This
will be supported with version 0.7.7 of JaCoCo, scheduled on May 14.
ProgrammingLife2016/PL2-2016