Merge pull request #9 from writetoritu/master

Modified "Vitals" query and minor changes to documentation
r3.5

- Change mapping logic for DRG and DRG type
- Change mapping logic for BP position
- Complete INSERT
Update vital query to implement new conventions for blood pressure:

By convention, systolic BP will be consider the "anchor" observation.
The corresponding diastolic BP and BP position will store the
observation_id of the systolic BP in their "value_as_concept_id" field.
For consistency, although redundant, the systolic BP observation will
also store its observation_id in it "value_as_concept_id" field. Thus
all three observations will be tied together by the observation_id of
the systolic BP observation.
r3.51

Minor fix
Merge pull request #3 from OHDSI/master

updating with the OHDSI master