Add additional handler in the step "Check for null or. in data_value" where it will drop null data values when value equals to 'null'
adjusted insert into observation_fact 

To meet constraint defined on table.
Used "TrialID" to fill "modifier_cd" column (this is expected in advanced analysis)
changed insert into observation_fact

"modifier_cd" filled with "study_id".
Adavance work-flow analysis expect this.
adjust oracle sql syntaxes to postgres sql syntaxes
Merge remote branch 'origin/master'
Create median.sql
Create transmartApp-DB_Post.sql

Temporary solution to fix some omissions in the Postgres database.
These are needed to get "i2b2_load_clinical_data()" running successfully.
Merge pull request #2 from thehyve/master

Make ETL pipeline more robust for null values