Release 0.4.2

[PLAT-33341] Add Caffeine interface to limit Sjsonnet worker cache si…

…ze (databricks#128)

- The current map-based parse cache is now DefaultParseCache
- The new ParseCache abstraction can be used to supply other cache implementations

Merge pull request databricks#118 from szeiger/release-0.4.0

Bump version to 0.4.0

bump uJson version to latest

Merge pull request databricks#89 from szeiger/prepare-0.2.7

Update for release 0.2.7