Improved validity range, so that end date and start date are available;
Changed PgLocalDateTimeRange from DefinedRange to ValidityRange;
Updated build.sbt, no scala 2.11 due to slick
Merge branch 'master' of https://github.com/nicocoffo/scala-slick-extras into nicocoffo-master

Conflicts:
	build.sbt
	version.sbt