Added support for new RPC support using HTTP POST. RPC's
arguments and reply are Gob encoded and sent as HTTP
request/response body.
This patch also removes Go RPC based implementation.
This makes lock RPCs similar to other RPCs where requests to the local
server bypass the network. Requests to the local lock-subsystem may
bypass the network layer and directly access the locking
data-structures.
This incidentally fixes#4451.
Current log prints in this form
```
ERRO[8150] Lock maintenance failed to remove entry for write
lock (should never happen)%!!(MISSING)(EXTRA ....
```
Fix this by using proper formatting directive.
* Rename GenericArgs to AuthRPCArgs
* Rename GenericReply to AuthRPCReply
* Remove authConfig.loginMethod and add authConfig.ServiceName
* Rename loginServer to AuthRPCServer
* Rename RPCLoginArgs to LoginRPCArgs
* Rename RPCLoginReply to LoginRPCReply
* Version and RequestTime are added to LoginRPCArgs and verified by
server side, not client side.
* Fix data race in lockMaintainence loop.
