Added support for defining keys in upload() via dicts (i.e. item.upload({'key1': 'body1', 'key2': 'body2'})). Added support for rsync-like directory copying (i.e. `ia upload <item> dir/` vs. `ia upload <item> dir`).
Log identifier on HTTP errors.
If the file being uploaded already exists on IA and the MD5 checksums match, skip uploading file.
Do not skip based on checksum by default, added as an option -- "checksum"
v0.5.7
Delete file if delete=True when skipping based on checksum. Log deleting file.
Merge remote-tracking branch 'upstream/master' into docs-testing