PersistentMap: untested SKV backend

Conflicts:
	CMake/FindPackages.cmake
	CMake/FindRequired.cmake
Servus: add API for continuous browsing
Add unit test

Conflicts:
	.gitexternals
	CMake/FindRequired.cmake
Fix travis
Merge pull request #131 from eile/master

Servus: add API for continuous browsing, SKV backend for PersistentMap
Unit test for lunchbox::Result, minor tweaks
Fix servus unit test with avahi
Merge pull request #132 from tribal-tec/master

Unit test for lunchbox::Result, minor tweaks
Servus unit test for broken update-during-browse
Breakup servus implementations
Fix VS2010 build
Merge pull request #133 from tribal-tec/master

Fix VS2010 build
Non-functional Servus avahi impl
Fix one bug in avahi announce
Fix another bug in avahi announce
add missing file
Unit test for lunchbox::Result, minor tweaks
Fix VS2010 build
Fix dnssd implementation and test
Fix avahi implementation