Added test to see if a dict containing integers can be properly converted to an etree.

This is needed because AnyDict can be assigned plain integers instead of a list of integers.
Added test for non complex value in root dict.
Test the cases where the value is None.
Enable use of AnyDict with values that are not collections.Sized (eg. they've got no __len__ method).
Do not convert strings into an array of characters.
Merge pull request #241 from specialunderwear/anydict-with-float-values

Anydict with float values
Merge remote-tracking branch 'arskom/master'
util.etreeconv: don't call str() on basestring instances. #241
fix util tests to adjust to the new datetime behaviour.