Default selectId function for EntityAdapter

[code2nguyen]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[x ] Feature request
[ ] Documentation issue or request

What is the current behavior?

I have several entities, and I use always id property for the primary key. So, to create the EntityAdater I must repeat the code like:

export const myEntityAdapter: EntityAdapter<MyEntity> = createEntityAdapter<MyEntity>({
  selectId: (myEntity: MyEntity) => myEntity.id
});

Expected behavior:

This could be greate if createEntityAdapter uses a default selectId method which will take id property of object as a primary key. So I just need call this function

export const myEntityAdapter: EntityAdapter<MyEntity> = createEntityAdapter<MyEntity>();

Minimal reproduction of the problem with instructions:

Version of affected browser(s),operating system(s), npm, node and ngrx:

Other information:

[brandonroberts]

Fixed via #405