Disable Seccomp when running old Linux kernel

Get kernel version when building, as well as testing for Seccomp headers

Fix #586
Use semver to compare kernel versions properly
Add semver, for build system
Fixing up dynamicEndpoints.py to properly read log messages again. This is going to have to be fixed any time InterfaceController.c changes...
Merge branch 'master' of git://github.com/clehner/cjdns into crashey

Minor changes to the implementation, skip the check if cross compiling and fixed merge.

Conflicts:
	node_build/make.js
Starting a rewrite of dynamicEndpoints.py
Switching dynamicEndpoints.py over to use a real logging system, and catching and logging some errors.
pipe stdout, stderr streams of child proccess to main process in make.js
Show error if gmake or make not installed
Show 'gcc is required!' if gcc not installed on build
Wrote config file parsing for dynamicEndpoints.py and an example config file.
Config file is now required for dynamicEndpoints.py, and help message is somewhat informative
Merge branch 'crashey' of https://github.com/cjdelisle/cjdns
Add --nobg switch
Merge branch 'no-bg-switch' of https://github.com/kpcyrd/cjdns into crashey
fixes #597 and tested on macosx and Linux
Merge branch 'nix_Jmp_callback' of https://github.com/wfleurant/cjdns into crashey
Use nobg switch in upstart script
Remove upstart nobg workaround
Use nobg switch in systemd unit