Include all adjustments in final shipment price

(Not solely promotions and taxes.) As per discussion in https://github.com/spree/spree/issues/5415

Fixes #5415
Fixes #5419
Fix broken specs from 4441fb42acfbf7ebf02a44c116f0d09d61c3b54f & c3a741c
refactor shipping calculator compute methods

clearer naming for methods

Fixes #5414
fix spec path in readme
Fixes #5423
refactoing code to call find_adjustment in before_action rather than calling it in each menthod
Fixes #5426
Add spec to ensure adjustment callback is fired.
Add comment explaining its important to use destroy_all.
Fix db:bootstrap task
Fixes #5431
Fixes #5432
Replace scoped with where(nil) as scoped was removed from Rails. See: http://stackoverflow.com/a/18199294 Fixes #5366
Add considered_safe to variable states

add translation for considered risky in order index

Add considered risky flag to orders index

Fixes #5374
Fix spec broken by 3eeb71d and add a regression check for it.
Add Canadian provinces. Fixes #5016