Refactor faasd and faas-containerd merge

The use of containerd and CNI functions has been refactored to reuse
the same codebase.

Added all network functionality to own directory and package. Removed
netlink and weave library in favor of using CNI plugin result files.

Rename containers handler to functions to clear-up functionality.

Signed-off-by: Carlos de Paula <me@carlosedp.com>

vendor/github.com/vishvananda/netlink/netns_unspecified.go

@@ -0,0 +1,19 @@
+// +build !linux
+
+package netlink
+
+func GetNetNsIdByPid(pid int) (int, error) {
+	return 0, ErrNotImplemented
+}
+
+func SetNetNsIdByPid(pid, nsid int) error {
+	return ErrNotImplemented
+}
+
+func GetNetNsIdByFd(fd int) (int, error) {
+	return 0, ErrNotImplemented
+}
+
+func SetNetNsIdByFd(fd, nsid int) error {
+	return ErrNotImplemented
+}