Destroy conntrack table on source host during migration

If a VM migrates from hostA to hostB, there will still be connections
in the conntrack table of the hostA. If, for any reason, VM is migrated back
to the hostA, while those connections are still in conntrack table, persistent
connections (such is ssh) to VM, from outside, will get dropped. They get
dropped cause hostA was expecting different packets and cause of that requires
establishing new connection. By dropping conntrack table entries for VM
we make sure that connection flow is not interupted by old packets.

Change-Id: If8e146e05914e9febd6fc40a1d8085306c1244ea
Fix VMware Hyper console url parameter error.

fix bug #1172177

Change-Id: Iab858741cba61f218c639d76fa80c047196bcc64
Refactor work with db.instance_type_* methods

Remove session parameter from public methods:
  *) instace_type_get
  *) instance_type_get_by_name
  *) instance_type_get_by_flavor_id

instance_type_destroy performance optimization:
  Get instance_type_ref without unnecessary extra specs

instance_type_access_get_by_flavor_id performance optimization:
was:
1 query get instance_type with joined extra_specs
1 query lazy load instance_type_projects
now:
1 query get instance_type id
1 query get all instance_type_projects that correspond to id

instance_type_access_add performance optimization:
was:
1 query get instance_type with extraspecs
1 query add instance_type_access
now:
1 get only instance_type id
1 query add instance_type_access

instance_type_access_remove performance optimization:
Same as in instance_type_access_add

blueprint db-session-cleanup

Change-Id: I6d1456289a97c46d7e8c9345474396c08e053970
Merge "Fix VMware Hyper console url parameter error."
Merge "Destroy conntrack table on source host during migration"
Merge "Refactor work with db.instance_type_* methods"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp