Remove some side effects and add an optional to save log to file as well.#1

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shawnLeeZX wants to merge 5 commits intobenley:masterfrom

shawnLeeZX:master

Commits on Nov 20, 2015

Commits on Mar 11, 2016

* Changed the default behavior to write log to stdout, since most time
shawnLeeZX
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Commits on Mar 26, 2016

Repeated calling init will not have any side effect now.
shawnLeeZX
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