Make unknown keys values mode visible

valueForKeyPath where silently returning null for unknown key, now it
returns the key name with a NOT_FOUND_ prefix.
localizedValueForKeyWithDefault now return returns the key name with a
NOT_FOUND_ prefix for unknowns keys. Those changes allows to locate the
missing keys very easily in the running application, without the prefix,
missing keys are less visible.
Selection binding is now updated when using inline template

Previously, the selection binding was not updated when using inline
template even without children elements. The inline parser create a
child element even when there is no in the html template. This created
problem with the condition used to update the selection binding.
Revert cb6907e3f8809d74f41c444aff2782bd1f89905a^..HEAD
Merge branch 'master', remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Merge branch 'master' of https://github.com/spelletier/wonder