HashUtil.pm: reverse order of hmac_sha1 arguments

HashUtil.pm: reverse order of hmac_sha1 arguments

Change the order of the arguments passed to HashUtil::hmac_sha1
to be "text" then "key" instead of "key" then "text".

Originally the hmac_sha1 provided by Girocco::HashUtil used the
sane order of "key" then "text" as that's the order they are
mentioned in RFC 2104.  The @#%^^@* Digest::SHA module, on the
other hand (which provides both hmac_sha1 and hmac_sha256), for
some inscrutable reason uses the order of "text" then "key"!

In an effort to avoid needless confusion, make the HashUtil
implementation of hmac_sha1 take the arguments in exactly the
same order as the Digest::SHA module's function of the same
name.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>