add zeroconf support based on qt4 libraries (#667)

* Removed -HUP so the default -TERM signal is sent instead.
- hyperiond only listens for TERM and INT. HUP is often used to get an exe to reread its config

Changed pgrep to add '-x' so it wont partial match on the exe name.
- I have multiple instances with multiple hyperiond-instance1 names
- this ensures the service script only kills the right process

* reversing errant change to hyperion.systemd.sh

* added bonjour/zeroconf service discovery to the json interface.

When clients are also modified, they can
- find hyperiond on the network much more quickly than ping/portscan;
- find multiple instances running on different ports instead of assuming 19444

* Moved zeroconf calls to hyperiond.cpp

* Added mDNS/zerconf/bonjour registration for proto server

Added config options.
        "jsonServer" :
        {
                "port" : 49444,
//              "mDNSDescr" : "hyperiond jsonServer blah de blah",
                "mDNSService" : "_hyperiond_json._tcp"
        },

* cleaned up a couple of compiler warnings

* moved bitpair_to_byte initialiser to (hopefully) work with older GCC

* compiler warning in udp driver
removed some tabs in ws2812b.cpp

* formatting - spaces to tabs

* moved rpi_281x to tag sk6812-v1.0

* moving to my fork of rpi_281x

* Now uses the led device name and hostname to create the annouce name


Former-commit-id: abfa51bcf359cafa63338181c1b83ecfd231bc87

HyperionConfig.h.in

@@ -30,4 +30,7 @@
 // Define to enable the osx grabber
 #cmakedefine ENABLE_OSX
 
+// Define to enable the bonjour/zeroconf publishing
+#cmakedefine ENABLE_ZEROCONF
+
 #define HYPERION_VERSION_ID "${HYPERION_VERSION_ID}"