Search request should end with empty line

[frankct310]

According to the UPNP document I found at http://www.upnp.org/specs/arch/UPnPDA10_20000613.htm the section 1.2.2, the search request message must have a blank line following the last HTTP header Another requirement is that the MAN header is enclosed in quotes

Fixing this allows me to find more devices like my marantz av receiver and LG tv. I assume this is the underlying cause of issue #4