Upload script won't work on drone v0.4

[foresmac]

Build steps on drone v0.4 don't have access to environment variables injected via the secrets file. Therefore, the upload script needs to check for the existence of CVR_TOKEN, and if it isn't available look for REPO_OWNER and REPO_NAME and send those params instead of a token. If all are missing, error out.

I.e.,

"${COVERAGE_URL}?owner=${REPO_OWNER}&repo=${REPO_NAME}&commit=${GIT_HASH}&coveragetype=${COVERAGE_TYPE}"