md-chips: Add a chip onInputBlur

[websirnik]

I think it's a good experience for md-chips to convert outstanding text to a chip when input loses focus.

Here is a use-case when it's relevant. User does not know that he needs to click enter to add a chip. When users clicks "Send email", no email has been captured.

[jproby]

👍

[nitinhayaran]

👍

[reillydavis]

👍

[Nikesh]

👍