Node.js 8 is now in maintenance LTS status and will be EOL in December 2019. Node.js 10 is now the active LTS version with Node.js 12 due for arrival in April 2019. Node.js 10+ provides an improved performance baseline as well as access to newer Node.js APIs and Javascript language features which the Angular CLI will now be able to leverage.
If no version specifier is supplied `ng add` will now try to find the most recent version of the package that has peer dependencies that match the package versions supplied in the project's package.json
This should clean up the code a bit.
Note: at first I added the no-useless-cast rule, but after getting frustrated
with it (as it has many false positive), I decided to remove the rule but some
useless casts were removed so I let those in the PR.
