Proper display of non-question Embeddables

[#48685567] This is the background and showing/hiding of headings for XHTML embeddables.
Change embeddable "Name" to "Heading"

[#48685567] This should help authors understand how the "Name" field is going to be used.
Adds "Question #x" headers. [#48685567]
Fix report-button color [#48685567]
Specs for question_index.

Validates the value and that it respects reordering.