0.12.3 minor feature release

Highlight:

• We want to introduce CustomSampler in this release. The base code is already there before but not documented.

Changes:

• Updating Type definition for CustomSampler.
• Updating doc/sample for introducing CustomSampler.

0.12.2 bug fix release

bug fix:

• Remove the "process.exit(0)" when master shutdown, which would accidental stop the process. The process shutdown should be up to user to run.

0.12.1 release (First workable release)

fixed issue that compiled js not published to NPM module