Fix MD5 comparison with s3 compatible servers that are not Amazon S3.

Some servers (like fakes3), doesn't add quotes in ETags aroung md5 value.
Ex.:
AWS: <LastModified>2014-06-05T09:45:25.000Z</LastModified><ETag>&quot;fc0f71ccc63dda0efc30239b48bdeccd&quot;</ETag><Size>132947133</Size>
FAKES3: <LastModified>2014-06-05T09:58:35.982060ZZ</LastModified><ETag>fc0f71ccc63dda0efc30239b48bdeccd</ETag><Size>132947133</Size>
(Nota: &quot; <=> " )

Bug in the previous code was always striping and first and last characters whatever they were. Such, in a fakes3 case, dest md5 was truncated and so would never match.
In the same time, this patch normalize the behavior to always strip " and ' chars in all the code dealing with etags.