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Merge branch develop, fixes #30
Add new methods to readme
Bump version number
Update changelog
New build
Add link to worker example
Add .only property
Merge branch 'master' into develop

Conflicts:
	CHANGELOG
Prevent error when calling ctor w/o arguments
Allow calling ctor with ready callback as only arg
Indentation
Prevent db version to become NaN
Add info to changelog
Add getBatch() method
Update changelog