Fixed the retrieval of the value of options

[stof]

The DOM property should be used rather than getting the attribute directly, to support properly elements which have a fallback behavior when their value attribute is missing (option elements are using their text in such case).

This fixes the test failure for options without values. refs #98

[aik099]

Do we have a test that covers this?

[stof]

yes. See the failure number 5 in the issue #98

[aik099]

I guess you can mention failure numbers in other two PR's you've made today as well.

[stof]

already done :)