Allow specifying viewDate as a prop, fixes #468

[vishy1618]

Description

Optionally specify the month that is viewed when opening the date picker without having an explicit value set.
The default behavior of viewDate is retained as well.

Motivation and Context

• This allows users to open the calendar at a specific month without setting the value. This is useful when we want the user to start from/choose a specific month.
• This fixes Open calendar to specific date (without *setting* the date) #468

Checklist

[x] I have added tests covering my changes
[x] All new and existing tests pass
[x] My changes required the documentation to be updated
  [x] I have updated the documentation accordingly
  [x] I have updated the TypeScript 1.8 type definitions accordingly
  [x] I have updated the TypeScript 2.0+ type definitions accordingly

[vishy1618]

Hi, any updates on this? Would you require anything in addition to make the PR more complete?

[simeg]

Hey @vishy1618. Sorry about the delay! Thanks you for your contribution. Everything looks good so I will merge this.

[keithpickering]

Hey @vishy1618 could you let me know if I'm doing something wrong? viewDate doesn't work at all for me. See #644