Docs and fixes for 6.0 (angular#2316)

* Brought a fix in from `5.4.2` ([angular#2315](angular#2315))
* Fixed `@angular/fire/analytics` attempting to use `global` ([angular#2303](angular#2303))
* Fix the error message on storage ([angular#2313](angular#2313))
* Starting on documentation for 6.0

Removing the problematic share from the zone.js changes (angular#2315)

* Removing the problematic share from the zone.js changes
* 5.4.1 & changelog entry
* Dropping the cache and matrix from travis, as I have in master

Changelog 5.4.1

Changelog 5.4.0

Skip CloudBuild tests for now

chore: Release v6 rc.0 (angular#2302)

* Simplify travis, cache seems to be taking far too long
* Bump versions
* Changelog entry
* Dropping the tests from the Cloud Build run

Cloud Build is responsible for generating our NPM artifacts, however I am planning on moving to Github Actions for this so the community has more visibility. Our Cloud Build image doesn't current have java, so the new emulator powered tests are failing. Rather than invest more in the Cloud Build scripts I'm just commenting out the test runner for now.

chore(release): 5.3.0 changelog

Fix proxy in Node, get component name for analytics in both JIT and AOT

More strict types

Flushing out RC more and fixing SSR issues