#### Bug, feature request, or proposal:
feature request

#### What is the expected behavior?
I'd like to use something like this (just like `mat-menu`):
```
Open it

Dialog Title

Content


Cancel
Confirm

```

#### What is the current behavior?
Doesn't exist as fat as I have seen in the docs and source code.

#### What are the steps to reproduce?
I've created a small component which demonstrates what I'm looking for:
https://stackblitz.com/edit/angular-material2-issue-tp5aej?file=app%2Fapp.component.html
(I didn't get `mat-dialog-close` working with the projection, though I chose to just add a method to my dialog component)

#### What is the use-case or motivation for changing an existing behavior?
There are many use cases where I just want a very simple dialog, and don't want to write 30 lines of code.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Angular 6 beta
Material 6 beta

Start with the linked StackBlitz example, particularly app/app.component.html, and compare the requested inline mat-dialog usage with the existing Material dialog docs and source. Determine whether projected content and mat-dialog-close can be supported, then define the API and tests needed for opening the dialog and returning the selected result.

Written by the indexing model from the issue text.