fix the bug findAndCountAll not working on postgresql.

copy `where` array, avoid changed by internal.
Merge branch 'master' of https://github.com/sequelize/sequelize
add test case for `does not modify the passed arguments - count`
add test case for count `does not modify the passed arguments`
fix copy/paste mistake
remove side effect in Util.format to fix bug `some function will modify passed arguments`.
Merge pull request #899 from hackwaly/master

fix the bug `findAndCountAll` not working on postgresql.
Don't clone options in find and findall, since this is taken care of in Utils.format