Fix formatting and add ascp password env variable

There were a few problems with the new configuration that we got after
contacting EBI, in short:
    - Passwords had to be updated, so we've centralized the retrieval of
      the credentials to be only in this file for the subprocesses that
      need them.
    - There was a missin `"` in the formatting of a string to generate
      the CURL commands.

--------

Please note that once this branch is merged into master and deployed, we will have to modify the profile file for the system to be in concordance with this change set.