Remove eth1 deposit functionality (#1780)

## Issue Addressed

- Resolves #1727

## Proposed Changes

Remove the `lighthouse account validator deposit` command.

It's a shame to let this go, but it's currently lacking any tests and contains significant, un-handled edge-cases (e.g., it will wait forever until the eth1 node gives a tx confirmation and if you ctrl+c it before it finishes it will leave the filesystem in an unknown state with lockfiles lying around)

I don't think we need to make deposit functionality a priority before mainnet, we have bigger fish to fry IMO.

We, will need to revive this functionality before the next testnet, but I think we should make private, non-production tools to handle this for SigP internally.

## Additional Info

Be sure to re-open #1331 if this PR is abandoned.

account_manager/src/validator/mod.rs

@@ -1,5 +1,4 @@
 pub mod create;
-pub mod deposit;
 pub mod import;
 pub mod list;
 pub mod recover;
@@ -29,7 +28,6 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                 .conflicts_with("datadir"),
         )
         .subcommand(create::cli_app())
-        .subcommand(deposit::cli_app())
         .subcommand(import::cli_app())
         .subcommand(list::cli_app())
         .subcommand(recover::cli_app())
@@ -47,7 +45,6 @@ pub fn cli_run<T: EthSpec>(matches: &ArgMatches, env: Environment<T>) -> Result<
 
     match matches.subcommand() {
         (create::CMD, Some(matches)) => create::cli_run::<T>(matches, env, validator_base_dir),
-        (deposit::CMD, Some(matches)) => deposit::cli_run::<T>(matches, env, validator_base_dir),
         (import::CMD, Some(matches)) => import::cli_run(matches, validator_base_dir),
         (list::CMD, Some(_)) => list::cli_run(validator_base_dir),
         (recover::CMD, Some(matches)) => recover::cli_run(matches, validator_base_dir),