Added NSUUID+Misc.

This has UUIDStringBase64url, which returns the base64url-encoded
representation of its UUID.
Add NSString+MD5.

This has an md5uuid method, which returns the MD5 of the NSString,
encapsulated in an NSUUID.
Add DNSQuery.h to the CopyFiles build rule.
Use the new NSData calls in iOS 7 to replace some of our own code.
Fix all the whitespace errors and turn tabs to spaces.
Add normalizeIso8601_24 and iso8601String_24.

These use the 24-character form of the date format (i.e. with msec
and the Z suffix).

normalizeIso8601_24 takes any ISO 8601 date form, and normalizes
it to 24 characters.

iso8601String_24 just returns the string in that 24-character form.