Add support for getting only portions of objects via HTTP range requests

[greenlion]

I made getObject() take a forth parameter. Now the third or fourth parameter may be an array (the forth is an array if the third is a filename or resource). If an array is passed in, then it should have two indices [0] and [1] which point to start and end bytes, respectively.

ie:
$first_ten_bytes = S3::getObject($bucketName, $uploadName, array(1,10));

Of course, if no range is passed in, then the whole object is retrieved.

[greenlion]

sorry it is a bit of a dirty push. I was in a hurry. I can clean it up and make any changes you request if you like. I didn't see issue #10, I just wrote this for myself and pushed it.

[greenlion]

did you add this functionality? if not, can you pull it as is. it has languished. if you don't want to pull it, what changes to do you want?