* Update vrrp.[ch] file header to be more accurate
* Make vrrp_update_times() private again
* Add times reset function and use it
* Add priority and advertisement interval setter functions and use them
* Add command to change advertisement interval
* Allow showing all VRRP instances
* Improve doc comments on functions
* Add ability to shutdown router
* Reorganize vrrp.h
* Add doc comments to vrrp.h
* Fix bug where Skew_time was not used to compute Master_Down_Interval
Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>