Examples and doctests should handle errors properly (no panics)

[liranringel]

Looking in the examples and even the doctests, errors are not handled properly (a lot of uses of unwrap and panic).
Tokio should follow the best practices because it's a core component of the Rust ecosystem. It may mislead newbies that copy-paste those examples.
Today we have the ? operator and can return errors from main, so it's not harder to do so. It is also recommended by the api-guidelines: https://rust-lang-nursery.github.io/api-guidelines/documentation.html#examples-use--not-try-not-unwrap-c-question-mark

[SanchayanMaity]

I would like to contribute to this. To clarify, would use of "?" be recommended or match arms are more preferable or it is better to select depending on the particular context? @carllerche @liranringel

[liranringel]

@SanchayanMaity
Usually "?".
I already changed most of the examples, I'll probably push it this weekend.
You do the doctests, ok?

[SanchayanMaity]

@liranringel Ok.

[carllerche]

I'm 👍 with this.

[liranringel]

This issue has been resolved :)