start of work
add a minimal mapReduce engine
Array.sum is missing :-(
emit can not be called
handle exception
refactor to be less ugly
Merge branch 'project-string' into mapreduce
Merge remote-tracking branch 'github/master' into mapreduce
Merge remote-tracking branch 'github/master' into mapreduce
Merge remote-tracking branch 'tw/mapreduce'
compile fix and test ignore

FongoMapReduceTest.testMapReduceSimple is failing, so @IgnoreD