Update instance.js
Only do parseInt when value is an string. 

OK, I test and also found for boolean(true), it is incorrect. So it will test string first.
Another Question, should we need to support string value "true" and "false" as boolean(true) and boolean(false) here?
add space in expression
Merge pull request #2187 from jchbh-duplicate/master

Fix an bug: Boolean always return true in mysql when column define has attributes of ZeroFill and Unsigned.