Updated gradlew to v2.1 and PMD to v5.2.1
Add support for 'years between', 'days between', etc., plus updating </<=/=/>=/> to support uncertainties
Add CQL execution support for milliseconds in CQL dates
Bumped up gradle to v2.2
- Added 'maven' plugin to java projects
Merge pull request #3 from esteban-aliverti/maven-friendly

- Added 'maven' plugin to java projects
Fixed several issues with CQL annotations not generating correctly.
Added an IdentifierRef to support emission of unresolved identifiers.
Add custom PMD ruleset and fix existing violations
Add support for timezone offsets to CQL execution
Refined context handling for patient information.
Added patientBirthdatePropertyName to modelinfo.
Added default Patient expression for Patient context.
Added CqlTranslator class and refactored cql-to-elm tests to use it.
Added SingletonOf syntax and ELM representation to support extraction of one and only one element from a list.
Refactored CqlLibrary to use CqlTranslator.
merging master into context branch