Error logging and examples

[rimutaka]

Issue #, if available: #241, #232, #216, #215

Description of changes:

1. Replaced tracing with log
2. Added error logging to
3. Added an extensive example with error logging options
4. Removed simulated feature from Cargo.toml
5. Added dev-dependencies to Cargo.toml
6. Updated crates via cargo update
7. Added readme.md to /lambda/examples/
8. Removed some commented-out code at the end of client.rs
9. Added comments to hello.rs and hello-without-macros.rs

Please, review the code carefully. I am new to Rust. Your comments and corrections are very welcome.

Important

I was unable to test this line from client.rs:

error!("Got error serving connection {}", e);

By submitting this pull request

• I confirm that my contribution is made under the terms of the Apache 2.0 license.
• I confirm that I've made a best effort attempt to update all relevant documentation.

[davidbarsky]

Thanks for opening this PR! A decent chunk of these changes have been landed in this branch. Can you rebase your README.md changes + examples atop of this branch?

Some of the comments are on your fork, by way, not on this PR. Can you comment on this PR in the future?

[rimutaka]

@davidbarsky, I'll rebase once we have a resolution on tracing.

[Veetaha]

LGTM with a couple of points otherwise 👍

[bahildebrand]

This looks good to me, but I wanted to be sure we addressed everything in previous reviews. @rimutaka @davidbarsky it appears there was some disagreement about removing tracing, but as far as I can tell tracing is still present. There was mention of a discussion in your fork, but I can't find it. Was this issue solved out of band? If so I'm comfortable approving and merging.

[bahildebrand]

I've got a branch up here that fixes all of the merge conflicts. It doesn't look like your branch is set up to accept commits from maintainers, so if I don't here from you in a few days I'll open a PR from that branch.

[coltonweaver]

This has been moved into: #284

The other PR just fixed merge conflicts and whatnot. Thanks for your contribution!

[seanpianka]

Apologies for bumping a closed issue. What is the motivation for migrating from tracing to log?

[rimutaka]

@seanpianka , the tracing is still there. https://github.com/awslabs/aws-lambda-rust-runtime/blob/master/lambda-runtime/src/lib.rs#L21. There was a discussion that it's overkill, but no action was taken to replace it with log or anything else.