Use JSON call to get the help topic

Also upped the z-index of ui-dialog in admin theme because help text fell behind top banner
Changes to translatable text will cause all existing translations to be lost.

If you are just correcting the English text (e.g. spelling/puncutation) and do not want the translated text to change, then you must also update the corresponding `msgid` in each of the .PO files.

If this is a change to the *content/meaning* of the English text (as in this case), you must **also** update the corresponding `msgstr` in the .PO files.

(NOTE: Having markup in the translation strings like this is bad practice - for this reason.  But this text was probably inherited from PGV.)

(NOTE2: This only applies to .PO files that contain a translation.  If the text is untranslated for any particular language, then it is not necessary to make this update, as there is no translation to be lost...)