v1.1.0--fix the problem of too long route synchronization time, and update the advertise-service-cluster-ip-range function.

--The function of advertise-service-cluster-ip-range has been updated.
--bgp-graceful-restart-ipv6 function is added to solve the problem of repeated packet transmission in the IPv4 scenario.
--Also dep is no longer used, we will be using go modules going forward for dependency management.
--Go 1.13 is version used for building kube-router and gobgp binaries.
--Starting from this release kube-router by default tries to auto-configure MTU for both pod interfaces and kube-bridge bridge interface.
--Fix the problem of too long route synchronization time.
--k8s.io/client-go, k8s.io/apimachinery, k8s.io/api are updated to v0.18.8.
--gobgp is updated latest version 2.19.
--Fixed some bugs.