better handling of sura/ayah urls

[ahmedre]

• some people try urls like quran.com/3:42 - while these aren't the standard, we should handle them (redirect to /3/42).
• when people use ranges, sometimes they flip the range (i.e. /23/5-4 instead of /4-5 - let's fix these if we can ).
• non-existant ayahs Non-existant ayat should return 404 but returns 500 #468

[atalebagha]

PR for this issue: #475

[mmahalwy]

Thank you!