allow newer versions of requests
add a few more shipping services
allow setting of units for size and weight
(seems to be needed for non-us senders)
add method get_label
(use-case: store label-data in a database instead
of a file)
send latin-1 encoded xml
(avoid problems with non-ascii characters)
add a comment about package type codes
depend on requests 0.14.2
(technically this is not a requirement but a
precaution)
Merge pull request #1 from till44/master

More shipping services, tweaks for non-us senders et al.