Added additional options in normalizer to more properly deal with missing values.

Fixes#168
small additional output fix.
Additional changes for VOC an Microbiome analysis.
gui fix
additional fixes after comments HJ
Small error fix
Fix in quantile normalization with missing values.
Small fixes and improvements
Merge branch 'master' of https://github.com/molgenis/systemsgenetics
Merge pull request #171 from Bonder-MJ/master

Added additional options in normalizer to more properly deal with missing values.