Refused to get unsafe header "tus-version"

[PVince81]

Since the addition of TUS we are now checking the TUS capability from the backend by reading the "tus-version" header.

If that one is not available, we should fail silently.

When using OC 10 as backend we get the error Refused to get unsafe header "tus-version" because it's not part of CORS.

I suggest we add a try/catch block in the SDK when parsing responses

[PVince81]

Attempt 1: trying try/catch around the get call => 💥

Attempt 2: trying to read the list of exposed headers before getting the unsafe header:

🤯

[PVince81]

Attempt 3: using getAllResponseHeaders to check beforehand whether the tus header is there without tripping over that error

[PVince81]

attempt 3 successful, PR here: #463