set consul-tempalte's vault default lease
set consul-tempalte's vault default lease

Consul-template grew a configurable default lease time for vault but
it did it in a way that made envconsul use a 0 lease time.

This fixes that by setting the default lease time to the new default as
specified in vault's config (in consul-template).

hashicorp/envconsul,hashicorp/envconsul