Netgrasp

* 7: do not cache DNS forever

* 13: properly detect when device changes IP

* 2: added HTML-based (and improved text-based) emails
* fixed lock issues, further lock-debug improvements
* bug fixes

* simplified/optimized logic within locks
* improved locking debug
* 3: fixed `netgrasp list` bug to no longer show 'never' seen devices
* fixed `netgrasp start --foreground` flag to not daemonize

v0.8.0, 29-May-2017 -- Initial release.