update bundle gem version.

mysql2 v0.3.12 gem seems to be yanked. we updates v0.3.14 or later.
mussel,test: first natbox acceptance test.
mussel,test: add more instance/network_vif/external-ip lifecycle smoke testing.
dcmgr: fix missing timestamp entries for instance response.
Merge pull request #324 from axsh/external-ip-testing

External ip testing
add db migration to drop columns will be moved to sta.conf.
change sta.conf structure to localize each driver specific configuration.
update `POST /volumes` endpoint to adapt new volume model association.
mussel: add "volume create" sub command.
sta: update backend to create/delete zfs volume.
dcmgr: instance boot/terminate for iscsi volume.
Merge pull request #322 from axsh/fix-instance-response

dcmgr: fix missing timestamp entries for instance response.
Merge pull request #321 from axsh/bundle-update

update bundle gem version.
dcmgr: fix `PUT /volumes/vol-xxxx/attach,detach` endpoint.
mussel: add `volume attach`/ `volume detach` subcommands.
hva: add RHEL6 specific change and adapt for storage data model changes.
dcmgr: allow volume attach/detach for halted instance.
sta: rename LinuxIscsi to Tgt.
mussel: add "volume backup" subcommand.
sta: add backup_volume task.