Remove hack for BuildHive

Now that we deployed cpptasks-parallel to Maven Central, there is no
need to add a custom remote repository to the configuration any longer.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
README: adjust link

We renamed the repository in the SciJava org, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>