Set element_validate if using select_or_other

Problem/Motivation

By default the input fields get the element validator token_element_validate - however this breaks if the select or other form element type is used.
This form element type is used by google plus and opengraph metatags.
While opengraph ensures token_element_validate is replaced by select_or_other_element_validate - google plus doesn't.
This leads to notices / broken ajax because if them.

Proposed resolution

Use the same pattern as in opengraph.

Remaining tasks

Reviews neeeded.

User interface changes

None.

API changes

None.