Atlassian companion should respect OS level proxy settings

Summary

• Currently downloading and uploading files inside companion does not attempt to use proxy settings on the user's computer.  This causes uploading and downloading to fail.  It also causes JWT validation to fail so the to the user it never looks like Companion connected to anything.

Workaround

• Use the down/up arrow icons on the top of the page to download the document, edit and upload back to Confluence.