[Feature Request] Tree View in bootstrap-select among option groups

[mjain1994]

Is there a way to achievetree view in Bootstrap-select and also have nested option- groups. For now, I am planning to achieve the same using changing the styles (font, size, color) of options such that they look different, and having all the sub options getting selected, if a particular header option is selected.
Also, support for issue #737 for bootstrap-select-v1.13.0-beta version.

Looking for something like this (not the similar looks but similar functionality):

[caseyjhol]

Related: #180.