#22: split the StringNumberTest into StringIntegerTest and StringDoubleTest
#22: fixed a bug causing the reducer of ProfessionIndexMapred to fail
with Error: java.lang.RuntimeException: java.lang.NoSuchMethodException: hadoop08.util.StringDouble.<init>()
(covered by unit tests now)
#22: fixed same bug as in InvertedIndexMapred
in last assignmenmt (Hadoop reuses the value object while iterating in the reducer and just replaces the object's values)
#22: fixed expected output for ProfessionIndexMapred
Closes #22.