Only use joda's DateTimeZone not mix & match
Validate TimeZone in ConfigurationService startup
Use correct exception for missing required props

The one it was using was for when the service was already started
Renamed ServiceStartupException to *AlreadyStarted

Because that's what it is.
Use ServiceAlreadyStartedException correctly
Use StartupFailureException
extend StartupFailureException
Renamed exception class to *Exception
Removed redundant constructor
Throw runtime exception for internal error
debug level & use sl4j string interpolation
Added some comments
Added back call to TimeZone.setDefault

because we still have usages, but should always be the same in
production.
merge ScottDugas: Validate timezone on startup

Merge pull request #1557 from ScottDugas/sql-layer/validate-timezone
https://github.com/FoundationDB/sql-layer/pull/1557