Add CERN bundle instead of individual certificates

To prevent issues if individual certificates change their names in
future updates of CERN-CA-certs, as advised in:
https://cern.service-now.com/service-portal?id=kb_article&n=KB0008813

Dockerfile

@@ -177,9 +177,7 @@ ADD etc/grid-security/vomsdir /etc/grid-security/vomsdir
 
 # Create truststore for NXCALS Spark connection
 RUN yum -y install java-1.8.0-openjdk && \
-    keytool -import -alias cerngridCA -file /etc/pki/tls/certs/CERN_Grid_Certification_Authority\(1\).crt \
-        -keystore /etc/pki/tls/certs/truststore.jks -storepass 'password' -noprompt && \
-    keytool -import -alias cernRootCA2 -file /etc/pki/tls/certs/CERN_Root_Certification_Authority_2.crt \
+    keytool -import -alias cernbundle -file /etc/pki/tls/certs/CERN-bundle.crt \
         -keystore /etc/pki/tls/certs/truststore.jks -storepass 'password' -noprompt && \
     yum -y erase java-1.8.0-openjdk && \
     rm -rf /usr/lib/jvm/