Remove -lock and -lock-timeout for terraform init

[tonglil]

In order to use lock options in plan and apply, they have to be passed in init_options.
However, these options are used in terraform init.
But in 0.15, init no longer accepts these options.

Currently this blocks the use of lock options in 0.15 or higher.

Ideally these options are moved out of init into another parameter (like options).

https://www.terraform.io/upgrade-guides/0-15.html#other-minor-command-line-behavior-changes

The -lock and -lock-timeout options are no longer available for the terraform init command. Locking applies to operations that can potentially change remote objects, to help ensure that two concurrent Terraform processes don't try to run conflicting operations, but terraform init does not interact with any providers in order to possibly effect such changes.
These options didn't do anything in the terraform init command before, and so you can remove them from any automated calls with no change in behavior.

[jmccann]

oic, we set lock stuff in init_options but use it also outside of init command (e.g. apply at https://github.com/jmccann/drone-terraform/blob/master/plugin.go#L268-L273). But this isn't actually supported by init anymore.

So first step here is to fix so that 0.15 works by no longer passing to init. But a followup would be to refactor lock and lock timeout config from init_options to options.

[jmccann]

released with tag 8.3-0.15.1

[tonglil]

Exactly, thanks!