only use of helper(array) on Session::get() instead of Session::__construct

[samsonasik]

helper('array'); on Session class only used in get() method. So, moved the helper('array') usage to Session::get() method.

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[natanfelles]

While in the constructor, the helper function is called only once. In the get() will be called several times. I do not think it's a good change.

[samsonasik]

in other classes, use of helper is only when the helper functions will be called, it mostly for consistency

[lonnieezell]

While consistency is a good thing, in this case, I think it should stay in the constructor because @natanfelles is correct that we'll see it called a lot more than needed, and include_once is never the fastest command.