New account creation flow

**READY** for review & merge

**Depends on**:

- https://github.com/tidepool-org/blip-mock-data/pull/1
- https://github.com/tidepool-org/platform-client/pull/24
- https://github.com/tidepool-org/clamshell/pull/35

## What's it about

Implement a new account creation flow where you can:

- set up a care team for yourself
- OR set up a care team for someone you care for
- OR identify yourself as "just a caregiver"

## Migration

None required. All "legacy" accounts default to "care team is for myself". Can edit to switch to "care team is for someone else".

## Current progress

**Sun, June 29th (Done)**: Add unit tests for new core services. Add welcome messages and link to care team from account page.
**Fri, June 27th**: Add toggle on care team setup page to create a care team corresponding to another person (i.e. different than logged-in user). Add possibility to identify yourself as "only a care giver" so you don't get the "create care team" prompt all the time.

**Thu, June 26th**: First commit, switched to a new "client-side data model" for users and patients which I hope simplifies things a bit and is closer to what's going on in the backend (see below). At this stage no new functionality (but got all old functionality working with new model).

## Data model

On the client-side we now handle objects that look like this:

**Logged-in user**:

```javascript
var user = {
  "userid": "11",
  "username": "mary.smith@example.com",
  "emails": ["mary.smith@example.com"],
  "profile": {
    "fullName": "Mary Smith",
    "patient": {
      "birthday": "1987-03-08",
      "diagnosisDate": "1994-02-01",
      "about": "I like swimming"
    }
  }
}
```

**Patient == user**:

```javascript
var patient = {
  "userid": "21",
  "profile": {
    "fullName": "Charles West",
    "patient": {
      "birthday": "1982-06-07",
      "diagnosisDate": "2002-03-01",
      "about": "I like carrots"
    }
  }
}
```

**Patient != user**:

```javascript
var patient = {
  "userid": "31",
  "profile": {
    "fullName": "Sarah Carter",
    "patient": {
      "isOtherPerson": true,
      "fullName": "Jessica Carter",
      "birthday": "1999-07-03",
      "diagnosisDate": "2009-08-01"
    }
  }
}
```

**Logged-in user is caregiver only** (hides the "create care team" prompt):

```javascript
var user = {
  "userid": "51",
  "username": "dr.scott@example.com",
  "emails": ["dr.scott@example.com"],
  "profile": {
    "fullName": "Dr. Scott",
    "isOnlyCareGiver": true
  }
}
```

**New signup** (shows "create care team" prompt):

```javascript
var user = {
  "userid": "51",
  "username": "new.guy@example.com",
  "emails": ["new.guy@example.com"],
  "profile": {
    "fullName": "New Guy"
  }
}
```
I have been trying hard to push common datetime functions into sundial - do you really think this belongs here?