Fix upload to dir

[avanaur]

A brief description of the changes in this PR:

Fix upload to dir such that intention to upload to a directory works.

Resolves 0chain/blobber#715

Tasks to complete before merging PR:

• Ensure system tests are passing. If not Run them manually to check for any regressions 📋
• Do any new system tests need added to test this change? do any existing system tests need updated? If so create a PR at 0chain/system_test
• Merge your system tests PR to master AFTER merging this PR

Associated PRs (Link as appropriate):

• 0chain:
• blobber:
• gosdk:
• system_test:
• zwalletcli:
• Other: ...

[service-0chain]

Manual system tests [failure] with the following config

config	value
tests skipped	FALSE
system-tests	fix/blobber-715
gosdk	staging
zboxcli	fix/upload-to-dir
zwalletcli	staging
0chain	staging
blobber	staging
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging

[service-0chain]

Manual system tests [success] with the following config

config	value
tests skipped	FALSE
system-tests	fix/blobber-715
gosdk	staging
zboxcli	fix/upload-to-dir
zwalletcli	staging
0chain	staging
blobber	staging
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging

[service-0chain]

Manual system tests [failure] with the following config

config	value
tests skipped	FALSE
system-tests	master
gosdk	staging
zboxcli	staging
zwalletcli	staging
0chain	staging
blobber	staging
authorizer	staging
0box	staging
0block	staging
0dns	staging
explorer	staging
0proxy	staging
0search	staging