added interval schema in medications and some notes on ccda parser
Merge pull request #126 from amida-tech/schema-medication-interval-add

Interval schema in medications and some notes on ccda parser
simplified tests (old tests are disabled for now)
updated tests descriptions
top level identifiers
Merge pull request #127 from amida-tech/afsin

top level identifiers
fix performer (added code) and snake cased reference_range
Merge branch 'master' into dmitry-fix
Merge branch 'dmitry-fix'
version bump to beta 6
updating medications
added preliminary changes to npi parsing, in addition to support for two types of names in performers
transformed provider fields to performers to match ccda
allowed common performer to take on person name or string name, added fixes to performer
made npis into identifiers
updating plan of care
added code system to vitals, blood pressuures, height, weight
removed medicare pin from parsing
fixed schema discrepancies in CCDA
bump to beta 7