[TASK] Set default values with properties in Domain
[TASK] Domain: Remove setter for creation time

A setter for the creation time does not make sense, as it is set in the
constructor (and should not be changed afterwards).
[TASK] Domain: Rename idnaName to punycodeName
[BUGFIX] Behat: Database not reset between tests

The @fixtures annotation is required by FlowContext for the database
reset. The alternative to this commit would be to have a method that is
annotated with @BeforeScenario in our FeatureContext that in turn calls
the resetTestFixtures method of FlowContext.
[BUGFIX] Multiple domains with same name can be created

Resolves: RP-37
[FEATURE] Behat: create user before logging them in