Fix/map tests

Fixes for $.map() tests and $.map(<object>, ...)

1. Any error messages from the console => actual tests for map() fail:
- TypeError: Object div1 has no method 'join'
- TypeError: Object 0a has no method 'join'
- TypeError: Cannot call method 'join' of undefined

2. Line numbers of offending code
appframework.js, line 282

3. Test cases
use tests from master and from this commit

4. Description of the error
- the tests used wrong (JavaScript like!) syntax for callback (elt, index) instead of the »af-way« (index, elt)
- .get().join() breaks, because of changed return value in 18a26e1 (your Fix #347)
- in 18a26e1 in line 282 the .apply() is missing

5. Expected result
Tests without failures :))