[release] Set version numbers for 2.0.1 release.

Disable and hide explicit builders.

Update the README.md to reflect the release of Dagger 2.0, fixing up …

…some filler text, updating versions, and pointing at the right download/repository sources.

[maven-release-plugin] copy for tag dagger-parent-1.2.1

[maven-release-plugin] copy for tag dagger-parent-1.2.0

[maven-release-plugin] copy for tag dagger-parent-1.1.0

[maven-release-plugin] copy for tag dagger-parent-1.0.1

[maven-release-plugin] copy for tag dagger-parent-1.0.0

[maven-release-plugin] copy for tag dagger-parent-0.9.1

[maven-release-plugin] copy for tag 0.9