Remove faulty paragraph about plugin configs.

The dev-plugins documentation states:

"The plugin configuration is loaded only once and is then cached.
Similar to changes in 'gerrit.config', changes to the plugin
configuration file will only become effective after a Gerrit restart."

This is not true anymore:

“Flush global plugin config on plugin reload”
https://gerrit-review.googlesource.com/#/c/52524/

“Allow plugins to check for config updates when reading plugin config”
https://gerrit-review.googlesource.com/#/c/54060/

Change-Id: Iac588f1ff7b00ab47e084129a532edd5cf636c4f
Update locations of Gerrit's CLA text

Google has moved the CLA text to a new site.

Change-Id: If5f578d99c987f78a14aa7d674ea2d1a55735c2a
Hoist ContactStore configurtion out of WebModule

Move this up into Daemon and WebAppInitializer. This allows
gerrit-review to trivially bind its own ContactStore instead
of relying on SitePaths for the GPG key.

Change-Id: Ib71e073680657980ff2e4f6ba339b99127151e35