Feat: bhCurrencyInput to validate currencies

[jniles]

Component: bhCurrencyInput

This PR adds a currency input component (bhCurrencyInput) that uses the CurrencyService to validate currency inputs automatically. It takes in four bindings:

• model (two-way binding)
  The ng-model for the input. These changes are reflected in the parent
  controller
• currencyId (one-way binding)
  The currency id selected to validate the currency input with. This is
  selected elsewhere, but bound so that changes will propigate to
  change the validation state.
• form (one-way binding)
  The parent form in which the input resides. Used for validation
  triggers.
• validationTrigger (one-way binding)
  The trigger for when to show error messages.

The developer is expected to provide all of the above options. The currency input should be used in the form like this:

<bh-currency-input
  model="ctrl.model"
  currency-id="ctrl.currencyId"
  form="ParentControllerFormName"
  validation-trigger="ParentControllerFormName.$submitted">
</bh-currency-input>

Test Hooks

This PR also includes test hooks for developers to rapidly use the input in tests, without having to know the underlying details. You should be able to use it as follows:

// import from shared components file
var components = require('../shared/components');

it('works like a charm', function () {

  // sets the input value to an amount
  components.currencyInput.set(1500);

  // retrieves the value from the component.
  expect(components.currencyInput.get()).to.eventually.equal(1500);
});

Currency API

To keep with our current model of consuming APIs, this PR also introduces a /currencies API , which includes two methods:

• GET /currencies
• GET /currencies/:id

This new API replaces the previous route /finance/currencies and all client-side routes have been migrated to using /currencies. I've included integration tests as proof of work.

Closes #72. Closes #90.

[jniles]

@IMA-WorldHealth/local-contributors, all those working on components may want to look at this code for inspiration. It demonstrates:

1. Angular v1.5's angular.component() instead of using a directive.
2. How to write a test wrapper for a component and use in an e2e test (cash.spec.js)
3. How to document your component's usage, both in modules and in e2e tests.

@sfount, let me know if there is anything I can clear up in the PR text or the tests.

[jniles]

@sfount, could I get a review?

[sfount]

This idea of test utilities for directives is an excellent idea going forward. Very cleanly implemented.