Schematics: use `skipTests` instead of `spec`

[timdeschryver]

With the new version of the Angular CLI, the spec option from the schematics has been removed. Instead, a skipTests option has been added.

We would like to keep our schematics in line with the Angular CLI schematics.

This change includes:

• Modifying the schematic options
• Update the schematics code
• Uppdate the docs

For ref: angular/angular-cli@e92c46a

[Jefiozie]

I would like to work on it, if that is fine by you @timdeschryver

[timdeschryver]

Sure, go ahead @Jefiozie.
Feel free to ping us if needed.

[Jefiozie]

@timdeschryver thanks, I also see a change around style. Do you want me to change this I'm this issue/PR?

[timdeschryver]

Seems like I'm too late to answer 😅

[Jefiozie]

haha, yeah I thought it would be fine so made the PR 👍

[timdeschryver]

Yes, ofcourse - thanks!