Major problem with salt.output

@basepi @thatch45 this is a very bad regression here:

* Reloading sys is not a very good idea... even more nested in an imported module....
* Setting default encoding in such way can cause bad collateral damages on install where we use custom python modules and deal with internationnlized data where setting encoding is important. Moreover in python2, it is better to keep encoded strings in serialisations (like we do in Zope world)...
*  Third is the file test which can be an empty string in several situations, the if test addresses that.