config_remap: accept file paths relative to SYSCONFIGDIR
TS-2250: support inline configuration overrides in conf_remap

Add support to the conf_remap plugin for accepting configuration
overrides in the argument list. This makes it easier to override
only a few configuration variables (the common case), because a
separate configuration file is not required.
Update CHANGES for TS-2550
[TS-2541] Add WebSocket Support
[TS-2541] Add WebSocket Support