1.add DLedgerProxy to be the container of DLedgerServer.
2.add
ConfigManager to manage the config about DLedgerProxy and
DLedgerServer.
3.add DLedgerManager to manage the
DLedgerServers.
4.support configuration file startup.
5.start parameters
are compatible with the old version.
6.refactor the tests.

1.fix some tests for new model

1.code format

1.refactor the code and test

1.fix some test and add a new test

1.delete the print

1.fix some bugs and add some tests about leaderElector

1.add more tests about leaderElector

1.update conflict code

1.add startup args "server -c" to start with config file.
2.remove DLedgerRpcNettyServer#memstate.
3.check config before initialize DLedgerRpcNettyService.

1.remove DLedgerRpcNettyService#checkOnePort
2.remove printStack

1.use "groupId#selfId" to identify different DLedgerServer.

1.remove unused imports

1. make ConfigManager more flexible
2. refactor structure about
multi-raft
3. more friendly for updating version

…branch

1. fix incompatible code after merge master branch

1. refactor the main method in DLedger