[MONDRIAN-1687] Addressing bad rollups formed as a result of mishandling columns with nullAxisFlag.  There were 3 places where we were failing to account for nullAxis
correctly, resulting in bad CellKey coordinates and incorrect offsets.
 (cherry picked from commit 7b095a2)
Merge pull request #316 from mkambol/lagMon-1687

[MONDRIAN-1687] Addressing bad rollups formed as a result of mishandling columns with nullAxisFlag.