fix groovy map syntax error

tasx-4
let groovy generate getter and setter for email
make private method User.hash static
omit optional semicolons
factor out sha256sum
pad sha256sum with leading zeros
unit test User.sha256sum

tasx-4
create domain class Task
define Task fields and methods
let groovy generate getters and setters
create domain class Schedule
rename Schedule to Interval
rename and refactor fields and methods
store return values for tests