Update Rx View to invoke order-select hook (Fixes #74)

[dennispatterson]

https://github.com/cds-hooks/sandbox/issues/74

Other than find/replace changes, the following files were updated to account for the hook change:

• src/components/RxView/rx-view.jsx - update hook context from 'medications' to 'selections' and 'draftOrders'
• src/reducers/medication-reducers.js - assign an order id that can be referenced by 'selections' context

Also outstanding: By default, the sandbox discovers HSPC's https://fhir-org-cds-services.appspot.com/cds-services/cms-price-check service listening for the medication-prescribe hook. Logged https://healthservices.atlassian.net/browse/SNDBX-1170 to get an order-select version

cc: @kolkheang

[dennispatterson]

Note that the https://healthservices.atlassian.net/browse/SNDBX-1170 issue was logged erroneously and I've logged https://github.com/cds-hooks/sandbox-cds-services/issues/12 in its place