Add support for resuming uploads

[pocketarc]

Create a DEPLOY_RESUME_[project]_[hostname] file in the same directory as the deploy.ini while uploading. That file should be updated with every file that's uploaded (and the commit hash that is being deployed). This will allow for resuming deployments.

The file is deleted when deployment is over, obviously.

When hitting "deploy", if it finds a resume file, it'll resume the upload, finish the upload, and THEN continue deploying new commits.

[pocketarc]

Not necessary; the only reason I needed it was because I had problems sometimes with files that would cause the upload to stop, but I've since resolved this issue.