Access device contacts

The PWA should be able to access contacts from user's system with user's permission. This will allow one to directly select `name` from phone book.

**How should we accept data?**
Say one user selects a `Contact A` from the system. Prepare a `JSONObject` in following form:
`{
"name": "Contact A",
"mobile": "xxxxxxxx",
"home": "xxxxxxx",
"email": "abcd@defgh.jk"
}`
The data should be sent as the value in API. The BackEnd system will automatically accept this data. In case data has been fetched from the backend system, an `id` key value pair can be added in the Object.