Error parameter as first argument

[karaxuna]

In nodejs async functions we normally have first parameter as error and then other data. JXcore's loadMainFile function looks like this:

jxcore('app.js').loadMainFile(function(ret, err) {});

Should be:

jxcore('app.js').loadMainFile(function(err, ret) {});

Same is true for the callback of jxcore(...).call function.

[obastemur]

@karaxuna lets check this again and make this part of 0.1.0.0 (also mention on release logs as breaking feature)

[obastemur]

Better also update the samples on 0.1.0.0 accordingly

[karaxuna]

#114