Add capability check for gerrit stream connection

Capability for gerrit stream connection is tested as follows:

* NG: End of stream has been reached without any data
* OK: data is arrived
* OK: End of stream is not reached until timeout

This patch adds capability test to doTestConnection() according to the
above policy.
Add new interface and class for global plugin configuration

Some settings in each server configuration should be shared.
This patch adds new configuration class then moves them to this.

For backward compatibility, existing settings in server coniguration are
remained.

Fix for JENKINS-20120
Marks moved members and methods as deprecated in Config class.
Add member for PluginConfig

* Add member and getter method to PluginImpl
* Adjust BC
* Add convenient method to GerritManagement
* Change creation and starting process for GerritHandler
Implement to Jelly
Add copy constructor
Add test for PluginConfig
Handle "Any Server" when filling Verdict Category list and Project List auto-completion.

Change-Id: I927cbc01710e04c9f4aa257d33a5e09e228c5244
Back numberOfSendingWorkerThread and related method into Config
Name the gerrit send command threads
Avoid duplicates when loading project list of all servers.

First add to HashSet, then to ComboBoxModel.

Change-Id: I4c98a8d4040b9ae25423b431044551b0fd9bd832
Open a constant parameter "CMD_STREAM_EVENTS" to the public
Use constant parameter for gerrit stream
Merge pull request #95 from rinrinne/test-stream

Add capability check for gerrit stream connection
Merge pull request #98 from mathieu-wang/any-server

Handle "Any Server" when filling Verdict Category list and Project List auto-completion.
Merge pull request #102 from hugares/sending-thread-naming

Name the gerrit send command threads
Revert "Back numberOfSendingWorkerThread and related method into Config"

This reverts commit 23df5f1e7d1f9fc0d77c0594a78c2b77a36f0327.
Set transient to deprecated field
Remove interface class for PluginConfig
Fix checkstyle error