Deserializing Provider.proto to scheme

The replacement of proto to scheme caused a lot of deserialization warnings
in the Jenkins startup log.
Mentioned in a comment on Github:
https://github.com/jenkinsci/gerrit-trigger-plugin/commit/52281400a21c0288029c5db925a8942be6d31705#commitcomment-4308718

Change-Id: I23c896d300ac7af903b8743440fdc3c68c601f55
Added context menu for GerritManagement

Also fixed the breadcrumb for each server not being displayed.

Change-Id: I4b557f8d6d776efdce4f022d6e2f0ffaec5932d6
Merge "Added context menu for GerritManagement" into internal