Add refs being replicated to show-queue output of replication tasks

This change adds refs to show-queue output making it convenient to see
which refs are being replicated by each task.

By default show-queue output will be limited to show 2 refs.

The value 2 is chosen because whenever a new patchset is created
there are two refs to be replicated (change ref and meta ref), refs
needs to be limited since it will become inconvenient if there are too
many refs being replicated.

Gerrit admin can override this behavior by providing "maxRefsToShow"
config in replication config file, to show all refs gerrit admin can set
"maxRefsToShow" config to zero.

Sample show-queue output:
(retry 1) push aaa.com:/git/All-Projects.git [..all..]
(retry 1) push aaa.com:/git/test.git [refs/meta/config refs/heads/b1]
(retry 1) push aaa.com:/git/test.git [refs/heads/b1 refs/heads/b2 (+1)]
(retry 1) push aaa.com:/git/test.git [refs/heads/b1 refs/heads/b2 (+2)]

Change-Id: Iaf7b32a0ac5f029671757658174cfde4e07f365c
6 files changed
tree: 3abafe71bd88dc07ec3f5867a8df84ec1870b701
  1. .settings/
  2. src/
  3. .gitignore
  4. .mailmap
  5. BUILD
  6. LICENSE