Revert "Include apache math library used for reducer skew detection"

This reverts commit 8b64624eeb31b2a338eedc1288fa4717231ebacb.
Revert "revert the excluded from jar option that appears to not be necessary if mhc ivy config is correct"

This reverts commit 7d0fab10707289b490832e15a89ae400c90ee3da.