All-Caps

Don't reject flair for being all-caps if the flair actually contains no alphabetical characters at all. Flair like "..." (which might come up, say, for Robert Strong) would be rejected with an "All caps" message, which is misleading. Likewise a flair whose only alphabetical characters were more complex unicode that .upper() doesn't know how to capitalize would be rejected, potentially erroneously. Alternately, if it is the case that all flair should contain at least one alphabetical character, we should additionally enforce that under a different error message.