CLOUDSTACK-7143: try to fix jenkins problems with last 2 commits
CLOUDSTACK-7143: try to fix jenkins problems with last 2 commits

* bundle install needs to run before running the vbox cleaning scripts,
  so move prepare step before clean step
* feature branches have / in their name which is a bad character to
  put into filenames

GabrielBrascher/cloudstack,jcshen007/cloudstack,jcshen007/cloudstack,resmo/cloudstack,jcshen007/cloudstack,DaanHoogland/cloudstack,resmo/cloudstack,wido/cloudstack,wido/cloudstack,wido/cloudstack,GabrielBrascher/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,DaanHoogland/cloudstack,wido/cloudstack,wido/cloudstack,GabrielBrascher/cloudstack,resmo/cloudstack,wido/cloudstack,DaanHoogland/cloudstack,jcshen007/cloudstack,resmo/cloudstack,DaanHoogland/cloudstack,DaanHoogland/cloudstack,GabrielBrascher/cloudstack,wido/cloudstack,jcshen007/cloudstack,resmo/cloudstack,DaanHoogland/cloudstack,DaanHoogland/cloudstack,GabrielBrascher/cloudstack,resmo/cloudstack,jcshen007/cloudstack,GabrielBrascher/cloudstack,resmo/cloudstack