3993 Editing process for chapters should be more like that for works

https://code.google.com/p/otwarchive/issues/detail?id=3993

So! We had a problem where creating, posting, editing, and deleting chapters was a lot messier than doing the same for works. Now they should be a lot more alike.

* Puts the "* Required information" notice on the chapter form inside the form (instead of above it) so it's pretty and blue like the one on the work form. (Also changed the wording from "Required fields" to "required information" to match.)
* Puts the asterisk next to "Chapter Text" so it's properly marked as required.
* For "Work Text" and "Chapter Text," the asterisk is outside the translation string so there's no worry about it disappearing during the translation process.
* Title-cases some fields on the chapter form to better match the title-cased fields on the work form.
* Removes the "Delete Chapter" and "Discard Draft" buttons from the chapter form itself and places a single "Delete Chapter" link at the top of the Edit Chapter page, which is where the delete option is when editing works.
* Updated the confirmation text for deleting chapters to say, "Are you sure you want to delete this chapter? This will delete all comments on the chapter as well and cannot be undone!"
* Edit chapter page says "Edit Chapter" and new chapter page says "Post New Chapter." Both have the work title listed below. (The pages always had visible headings, but now the text is more like the text for works.)
* Likewise, the new work page says "Post New Work." (The text was always there, but now it's visible for consistency with the Edit Work page and the chapter pages.)
* Chapter preview page now says "Preview" on the top, much like works say "Preview."
* Preview page for chapters now has its buttons in a fieldset, just like the preview page for works does.
Unless I'm reading this wrong, it looks as if this might result in a string that says "Edit ChapterNew Chapter", which doesn't sound desirable?

Also if we're interested in different text for new chapters and existing chapters, it might be best to construct them separately so they can be translated without being shoehorned into the English syntax (ie wrap two separate ts() into an `if @chapter.posted?` block)