minor documentation update.
Merge branch 'refs/heads/patch/release-2.1.0' into release/2.1.0
minor test
Fixed bugs, the "o2.then" module is working as expected now.
Merge branch 'refs/heads/patch/release-2.1.0' into release/2.1.0
FIX: resolve needed to be noop'ed after chain.
implemented a very basic async logger.

And also did dome minor refactoring.
Merge branch 'feature/async-logger' into develop
Merge branch 'develop' into release/2.1.0

Conflicts:
	.gitignore
	CHANGELOG.md
	package.json
	src/o2/functional/package.json
	src/o2/then/package.json
2.1.0 continued.
version bump.
Merge branch 'release/2.1.1' into develop