Add passback and pullback to approval
Add histories to passback and pullback
"pullback" should use own requester
Add passback and pullback to approval
Add histories to passback and pullback
"pullback" should use own requester
Merge branch 'add_passback_and_pullback_to_approval' of github.com:zomeki/zomeki-development into add_passback_and_pullback_to_approval
Merge branch 'add_passback_and_pullback_to_approval'

Conflicts:
	db/schema.rb
Change "requested user" to requester
Change "operated user" to operator
Log not only passback and pullback but also approve
Send notification mail after passback and pullback