Need to add "X-App-Client-Signature" to allowed cors header

[mallochine]

currently seeing issue where browser sends "X-App-Client-Signature" header but gets CORS error because this header is not allowed by blobber.

Reproduced with this:

curl 'http://six.devnet-0chain.net:31305/v1/file/upload/f84eb5ed3eb37cd86faf784f81a9d32894fd6d8ac2f4ae0cea6244b529c5064e' \
  -X 'OPTIONS' \
  -H 'Connection: keep-alive' \
  -H 'Pragma: no-cache' \
  -H 'Cache-Control: no-cache' \
  -H 'Accept: */*' \
  -H 'Access-Control-Request-Method: POST' \
  -H 'Access-Control-Request-Headers: x-app-client-id,x-app-client-key,x-app-client-signature' \
  -H 'Origin: http://localhost:82' \
  -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36' \
  -H 'Sec-Fetch-Mode: cors' \
  -H 'Referer: http://localhost:82/' \
  -H 'Accept-Language: en-US,en;q=0.9' \
  --compressed \
  --insecure -i

[mallochine]

resolved by PR #197 , merged into master