start adding support for reading temporary credntials from the
instance metadata
convert metadata parsing to std::string, which cleans the code
up a fair bit
more work on IAM roles
remove space after : in x-amz header and now the authenication works
removed header debug that was ausing parse errors
works now!
added  -o iam_role=
iam credentials should update before they expire
fixed credentials refresh
update the docs