V4.0 major version release (may result in enrollment shift)

Depending on your usage of planout.js, upgrading to v4.0 may result in a shift in experiment parameter value assignment, and namespace enrollment. Because of this, we recommend that you only upgrade to v4.0 when you don't have any experiments actively running.

• Core compatible bundle fixes:
  • Core compatible namespace allocations now match core reference namespace allocations from python version of planout.
  • Core compatible interpreted experiment enrollment now matches core reference interpreted experiment enrollment from python version of planout.
• Separated the concerns of planout core random operations, and the planout API. The planout.js API (experiment, assignment, namespace, etc) are now composed with the random operations they are passed. This change has no effect on the usage of planout.js and only affects the development experience for contributors.
• Added planoutAPIFactory.js to keep planout bundles consistent, and to make it easier to compose new planout bundles with the random operations of choice.
• Made experiment & namespace names required to fix #57
• Fixes WeightedChoice with false-y choices.
• Fixes tests on windows + running the travis tests on windows as well if this is possible.