Adds return_reason option to create a return label.
Set http_proxy settings when initializing Request
Merge branch 'proxy'

* proxy:
  Set http_proxy settings when initializing Request
expose all tracking details
switch from fakeweb to webmock (fakeweb depreciated by vcr)
Add shipping document service
Add workaround to bypass documents which has no filename specified
Allow consumer to deal with missed files

Replacing with nil is a bad idea ;)
Merge pull request #38 from jlambert121/tracking_details

expose all tracking details
Merge branch 'webmock' of https://github.com/jlambert121/fedex into jlambert121-webmock
Add webmock
Merge branch 'document-specification' of https://github.com/yevgenko/fedex into yevgenko-document-specification
Update Readme.md
Bump version