Add usernames to build parameters

[fpoirotte]

This adds several parameters to the builds to reflect usernames, namely:

• GERRIT_TOPIC_CHANGER_USERNAME
• GERRIT_CHANGE_ABANDONER_USERNAME
• GERRIT_CHANGE_OWNER_USERNAME
• GERRIT_CHANGE_RESTORER_USERNAME
• GERRIT_PATCHSET_UPLOADER_USERNAME
• GERRIT_EVENT_ACCOUNT_USERNAME
• GERRIT_SUBMITTER_USERNAME

Each parameter contains the Gerrit login for the related account, as a companion parameter for the already-existing GERRIT_*_NAME and GERRIT_*_EMAIL parameters.

The reason I added these parameters is because we want to send notifications to users when a build succeeds/fails and the notification tool we use requires users to be identified using their username.

Currently, the lack of this information forces us to do a separate HTTP query against the gerrit server to retrieve the username based on the value of the GERRIT_CHANGE_OWNER_EMAIL parameter. This additional query causes issues for us because the connection with the gerrit server is sometimes unstable.

Testing done

I updated src/test/java/com/sonyericsson/hudson/plugins/gerrit/trigger/hudsontrigger/GerritTriggerTest.java to include the new parameters and ran the tests in that file.

Unfortunately, I don't have access to a Jenkins installation where I could do detailed testing of this change at the moment.
However the additions are very similar to existing code and should be easy to audit if needed.

I also ran the checkstyle & findbugs targets.

Logs for each of the targets can be found as attachments :

checkstyle.txt
findbugs.txt
test.txt

Submitter checklist

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