This PR doesn't change new projects to use 2.4 since I have seen some reports of possible problems in `@angular/*`.
Instead, it:
- removes the dependency restrictions on <2.3
- bumps related dependencies to the minimum that supports 2.4 (`rxjs@^5.4.2`, `ts-node@~3.2.0`)
- builds the CLI itself using 2.4
So if you want to install ts 2.4 in your new project, the CLI itself won't stop you.
Fix#6827
Adds following defaults to `.angular-cli.json` under `defaults`: `sourcemaps`, `baseHref`, `progress`, `poll`, `deleteOutputPath`, `preserveSymlinks`, `showCircularDependencies`.
They can be set via `ng set defaults.build.KEY = VALUE`.
Also removes `apps.0.showCircularDependencies`. This is not a breaking chance since it was only added in 1.3.0-beta.0.
Followup to https://github.com/angular/angular-cli/pull/6884#discussion_r125533830.
