Use bash; don't terminate on error

The entrypoint script didn't work well when used with docker-compose. Namely, setting the password failed.
Switching to /bin/bash fixed it for reasons unknown.

The entrypoint script used to quit on every error, even errors caused by manual interaction with
dsmc in the container. That made manual intervention and operations like restore difficult. Now it
keeps running.
1 job for master in 22 seconds
latest
Status Job ID Name Coverage
  Build
failed #93629
build

00:00:22

 
Name Stage Failure
failed
build Build
INFO[0015] Taking snapshot of files...                  
INFO[0015] RUN unzip tsm_dsmcert_linux.zip && rm tsm_dsmcert_linux.zip
INFO[0015] cmd: /bin/sh
INFO[0015] args: [-c unzip tsm_dsmcert_linux.zip && rm tsm_dsmcert_linux.zip]
INFO[0015] Running: [/bin/sh -c unzip tsm_dsmcert_linux.zip && rm tsm_dsmcert_linux.zip]
unzip: cannot find or open tsm_dsmcert_linux.zip, tsm_dsmcert_linux.zip.zip or tsm_dsmcert_linux.zip.ZIP.
error building image: error building stage: failed to execute command: waiting for process to exit: exit status 9
Cleaning up file based variables
ERROR: Job failed: exit code 1