Add name property to MultiSelect

[skhattry]

I'm submitting a ... (check one with "x")

[x] bug report => Search github for a similar issue or PR before submitting
[ ] feature request => Please check if request is not on the roadmap already https://github.com/primefaces/primeng/wiki/Roadmap
[ ] support request => Please do not submit support request here, instead see http://forum.primefaces.org/viewforum.php?f=35

Current behavior
Name property is blank for p-multiselect

Expected behavior
Name property should have an appropriate value.

• Angular version: 2.0.X
  4.1.3

• PrimeNG version: 2.0.X
  4.2.1

• Browser:
  Microsoft Edge.