Clarify UTF-8 and URL-encoding of names

Fixes two issues:

o Where UTF-8 and URL-encoding are mentioned, often the URL-encoding is
  mentioned first. This might imply that URL-encoding is key -- it's not.
  The clasic mistake is to simply URL-encode a string. This can result in
  illegal UTF-8. Example: ÿ (y-umlaut) is URL-encoded as %FF. Whereas,
  the correct UTF-8, then URL-encoding is %C3%BF.

o Where container and object names appear in headers (such as
  X-Versions-Location), the UTF-8 string must be URL-encoded. This fix
  clarifies the header descriptions of such headers.

Change-Id: I82dea0e789aab6eb9bf27a1e70b01de427d50b80