Support ngProjectAs

[MichaelRFairhurst]

I don't know very well how this works, but I think the basics of it is that I may have a component which selects itself based on a tagname,

@Component(selector: 'my-tag', ...)

and then find myself in a place where its really important that my tag actually be a div. In this case you can use ngProjectAs.

   <div ngProjectAs="my-tag">

This is not really enough detail to support ngProjectAs, but this could cause false errors if inputs and outputs were bound on that div which only matches the component when we take ngProjectAs into account.

It also is important for validating transclusions #48

[matanlurey]

I don't think there are any real uses of this. I'd make it P3/P4.

[MichaelRFairhurst]

Don't have a P4 yet, added P3

[MichaelRFairhurst]

Upping in priority since we found cases where its used