Set HAL debug level explicitly for e-server.

src/e-server:
	* src/ServerInfo.cpp (ServerInfo::ServerInfo): Initialize
	halDebugLevel.
	(ServerInfo::halDebug): Created (two versions).
	* src/ServerInfo.h: Include epiphany-hal-data from e-hal. New
	accessor methods halDebug (set and get), and new private data
	halDebugLevel.
	* src/TargetControlHardware.cpp
	(TargetControlHardware::initHwPlatform): initialize platform using
	halDebug from ServerInfo. No need to call e_set_host_verbosity,
	since called from init.
	* src/main.cpp (usage): Document new flag --hal-debug
	(main): Capture --hal-debug value.