fix for method scope and constants.
fix for constants.
require root .rb instead of model rb.
model migration for storage_nodes and volumes tables.

It has started to use the class table inheritance pattern for storage data
entities. Storage has different attributes for each device or protocol. CTI
pattern allows to store both common and specific attributes to the parent
and the children tables.

Model classes were changed as follows:

volumes
  +-> local_volumes
  +-> iscsi_volumes

storage_nodes
  +-> iscsi_storage_nodes
allow "vdc-manage host modify" to overwrite node-id.
do not overwrite C constant shortcut in endpoint class.
update endpoint for new storage models.
update backend for new storage models.
modify lxc driver for new storage model.
show short error message.
return account_id, was forgotten, from backup object WebAPI response.
replace default web server for vdc.sh to Apache2.

Apache2 is capable of chunked encoding for PUT method. so we use it
for development.
Merge branch 'feature-alarm' into feature-volume-localstore

Conflicts:
	dcmgr/lib/dcmgr.rb
use constants for state string literals.
fix issue that invoke_task does not return original return value.
update "POST /instances" to accept volumes parameter.
wait multiple volume setup before booting instance and finalize volumes in case of failure.
call sync rpc for updating state. do not make async call again!!
disk and vif template parameter to image table.
Merge branch 'feature-volume-localstore' into feature-volume-localstore