Remove code/logic for working with Vault grace

[catsby]

Part of #1266 . Remove all the code for the deprecated Vault grace field.

Fixes #1268

Tests:

[consul-template][remove-vault-grace](4)$ make test  
==> Testing consul-template
ok      github.com/hashicorp/consul-template    2.042s
ok      github.com/hashicorp/consul-template/child      1.695s
ok      github.com/hashicorp/consul-template/config     0.121s
ok      github.com/hashicorp/consul-template/dependency 6.181s
ok      github.com/hashicorp/consul-template/logging    0.048s
ok      github.com/hashicorp/consul-template/manager    3.334s
ok      github.com/hashicorp/consul-template/renderer   0.102s
ok      github.com/hashicorp/consul-template/signals    0.036s
ok      github.com/hashicorp/consul-template/template   0.120s
?       github.com/hashicorp/consul-template/test       [no test files]
?       github.com/hashicorp/consul-template/version    [no test files]
ok      github.com/hashicorp/consul-template/watch      1.058s

[catsby]

cc @eikenb

[eikenb]

Hey @catsby,

Thanks for the PR and sorry for the delay getting back to sooner. I'm working on some consul-connect integration right now but once done will be making another issue/PR pass through all my projects and will get to it then.

[catsby]

Hey @eikenb have you had a chance to review this?

[eikenb]

Thanks for your patience @catsby. I'm seeing if I can get a release out before the holidays and will take a look at this for inclusion.

[eikenb]

@catsby Looks good. Thanks again!

[catsby]

Thank you @eikenb !

[eikenb]

@catsby .. You might have noticed I didn't make the pre-holidays release as I hoped. I was ready like the day before and thought it wasn't the best idea to release right before being away for a couple weeks. I'm back on it now though and should have it out soon.

[catsby]

No worries @eikenb , thanks for the follow-up!