[refac] changed file names to integrate files over libxively and make it safe to use against different libraries and environments

Conflicts:
	src/libxively/io/posix_asynch/posix_asynch_io_layer.c
	src/libxively/io/posix_asynch/posix_asynch_io_layer.h
	src/libxively/io/wiznet/wiznet_io_layer.c
	src/libxively/io/wiznet/wiznet_io_layer.h
	src/libxively/xively.c
[tidy] removed not needed files