abort script on failure
collect arbitrary number of rpms from cmd line
Merge pull request #270 from reneme/fix_ci_installrpm_sh

FIX: ci/installrpm.sh does not handle rpm lists

The parameter handling of ci/installrpm.sh was broken. It was expecting three distinct rpm packages (namely: cvmfs, selinux and server), though the invoking EC jobs did provide paths to other rpms and in particular often more than three packages.
So far there was no failure, since only three packages were provided and the distinction was not utilized by the script at all. Additionally the cvmfs packages did not depend on each other. Thus if (say) cvmfs-server was provided as a forth package to ci/installrpm.sh it would just have been silently skipped from installation.

Now it broke since cvmfs-unittests depends on cvmfs-server and cvmfs-server was provided but skipped by ci/installrpm.sh. I fixed it by allowing an arbitrary long list of rpms to be installed by ci/installrpm.sh.