Move default value to collector itself from fatory

More over, it fixes a bug if user use factory without options,
because factory send null instead of nothing which break everythinh.

And then, it make the collecter easier to re-use
minor #13 Move default value to collector itself from fatory (lyrixx)

This PR was merged into the master branch.

Discussion
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Move default value to collector itself from fatory

More over, it fixes a bug if user use factory without options, because
factory send null instead of nothing which break everything.

And then, it make the collecter easier to re-use

Commits
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132fbb7 Move default value to collector itself from fatory