data model small fixes

made dates into strings in CCDA parser, fixed test
need to fix schema generation test (see JIRA ticket)
errors object in model, relaxed schema to be array of strings

updated docs/samples .000Z -> Z (removed milliseconds)
date schema refactored to support low/high/effectiveDate
snake_case everywhere, updated social_history model; date_time everywhere
updated CMS parser to "date_time" model with schema validation
added NegationId to allergies

per
https://github.com/PragueExpat/blue-button/commit/4c30c1397ba1391d9d5064
55975f9295bb9af3eb
snake_case negation indicator in allergies
email/phone cleanup
Merge branch 'master' of https://github.com/amida-tech/blue-button into 1.1.0-beta
Update plan_of_care.md
Merge pull request #37 from amida-tech/bjs-branch

Bjs branch
Merge pull request #38 from amida-tech/dmitry-pragueexpat-fixes

Dmitry pragueexpat fixes
first pass at plan_of_care parser. testing next
Merge branch '1.1.0-beta' of https://github.com/amida-tech/blue-button into 1.1.0-beta
plan_of_care parsing deep equal test passing
Update plan_of_care.md
plan_of_care object schema for validation and test for validator
Merge branch '1.1.0-beta' of https://github.com/amida-tech/blue-button into 1.1.0-beta
test for validator passing
ccda generation for plan_of_care section, basic tests passing
code cleaning test library