Update Joda-Time and fix min/max instant overflow

- Update Joda-Time for latest TZ updates and bugfixes
- Druid makes extensive use of Long.MIN/MAX_VALUE for timestamps, which can cause overflow issues in Joda and are not allowed anymore. Added a concept of MIN/MAX instants in JodaUtils to address that.
- Fixed a few places where DateTime(0) was used, when DateTime(MIN_INSTANT) was meant.