Remove data-action attribute in buttonEnabler

fixes #701 on github.

The 'Add Tree' anchor tags use a 'data-action' tag to enable the add tree mode. The button enabler removes this action in the case of disabling or redirecting, in order to prevent this behavior from leaking through.
Merge pull request #737 from steventlamb/bug/701/add_tree_not_redirecting

Remove data-action attribute in buttonEnabler