amrsreports: changing columns to data definition.
amrsreports: adding voided clause to the query.
amrsreports: changing the substitution string.
amrsreports: adding pmtct data definition
amrsreports: minor fixes on start stop drug evaluator
amrsreports: minor fixes on pmtct evaluator.
amrsreports: displaying only the first pair for the start and stop drug.
Merge pull request #57 from nribeka/data-definition

Changing logic columns to data definition.