Exception Handling: Errors from getContentAsStream() are logged too often

[predic8]

When body.getContentAsStream() throws an Exception like javax.net.ssl.SSLException it gets logged as ERROR and there are several stacktraces.

• Maybe we should not log this as ERROR. The cause is not a problem in Membrane, just the behaviour of others.
• We should know what is going on.

	public InputStream getBodyAsStream() {
		try {
			return body.getContentAsStream();
		} catch (IOException e) {
			log.error("Could not get body as stream", e);
			throw new ReadingBodyException(e);
		}
	}

	public InputStream getBodyAsStreamDecoded() {
		// TODO: this logic should be split up into configurable decoding modules
		// TODO: decoding result should be cached
		try {
			Message m = xopr.getReconstitutedMessage(this);
			if (m != null)
				return m.getBodyAsStream(); // we know decoding is not necessary any more
			return MessageUtil.getContentAsStream(this);
		} catch (Exception e) {
			log.error("Could not decode body stream", e);
			throw new RuntimeException("Could not decode body stream", e);
		}
	}