Tracking: Lower Install Time.

[hansl]

• Fork CompressionPlugin and remove Zopfli dependency.
• Make Sass Loader not directly depend on node-sass and install it only if/when needed.
• Remove direct dependency to protractor and show error message when ng e2e is run but protractor isn't in node modules.
• Remove direct dependency on karma and show an error message when ng test is run but karma isn't in node modules.
• Drop bootstrapping time down to under 1 seconds on Travis (or in e2e in general).

[hansl]

Forking CompressionPlugin happened in #3414.

[hansl]

Cleaned up the package json and made a script to make sure we always depends on the exact dependencies, not more or less.