Fixed support for 'Range' header

[SecurityForUs]

While I don't think the fix is 100% 'Pythonic', it reflects the fact that there are multiple scenarios for 'Range' header: http://docs.openstack.org/trunk/openstack-object-storage/developer/content/retrieve-object.html

I wrote a testing function that simulates this to demonstrate how it works in comparison to the above link:

>>> def tester(size=0,offset=0):
...     if size > 0:
...         if not offset:
...             print "bytes=-%d" % (size-1)
...         else:
...             print "bytes=%d-%d" % (offset, (offset+size) - 1)
...     else:
...         print "bytes=%d-" % (offset)
... 
>>> tester(offset=32)
bytes=32-
>>> tester(offset=5)
bytes=5-
>>> tester(5)
bytes=-4
>>> tester(5,10)
bytes=10-14

[CrackerJackMack]

Either the diff viewer is messed up or you used tabs?

[SecurityForUs]

im not sure what you mean. the commits were loading fine for me via github

[SecurityForUs]

I used tabs in some of them apparently, sorry about that. I fixed it w/ spaces now and it should be fine.

[SecurityForUs]

Didn't catch that one, sorry about that.

[sudorandom]

I'm going to close this pull request not because it wasn't good, but because there was one additional case that we found and wanted to support as well. If you look at the code and at the tests that we added, you can see why. Thanks for your input. We really appreciate it.

https://github.com/softlayer/softlayer-object-storage-python/commit/748353038499dba62b943065471d5f7ea941c4e6