* Update all dependencies

* Upgrade dependencies whenever “easy”

“easy” means that there are no major changes required.

* Fix build and bump paste dependency to 0.1.6

* Remove dead code

* Re-add = dependency for futures-preview

* Add missing std features for runtime-io

* Remove git dependencies

as updated versions have been published to crates.io

* try to debug bug

* For sr-io, "std" should imply "no_oom" and "no_panic_handler".

Otherwise, rustc complains (correctly) about duplicate lang items.

* Add missing "runtime-io/std" features

* Fix compilation errors

* Prevent duplicate lang items

Rust does not allow duplicate lang items.  When compiled without the
`std` feature, `sr-io` defines two lang items.  Therefore, `sr-io`
compiled without `feature = "std"` must not be linked with `std`.

However, `pwasm-utils` and `wasmi-validation` both bring in `std` unless
compiled with `default-features = "false"`.  This caused a duplicate
lang item error.  Building both with `default-features = "false"`
prevents this error.  When building with `feature = "std"`, they should
both be built with the `std` feature, so this feature needs to be
explicitly depended on.

* Bump `impl_version`

* Make tests pass

Three tests used 1 less gas than they had previously.

* Try to un-break build

* Add a Cargo.lock file

* Revert offchain code

* Revert "Revert offchain code"

This reverts commit d216d08cc6ca0344614669c1d24cde3aa5c0d4e2.

* Don’t try to send a body with a GET request

without adding a Transfer-Encoding or Content-Length header.

This has always been wrong, but hyperium/hyper#1925 hid the bug until
hyper was upgraded to 0.12.35.

* Change some more GET requests to POST requests

* Fix excess line width and remove an `extern crate`

* Delete commented-out extern crate

Co-Authored-By: Sergei Pepyakin <[email protected]>

* Fix regression in Cargo.toml files

dev-dependencies need `default-features = false`, too.

* Bump parity-wasm dependency

* Bump `futures-preview`

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <[email protected]>

* Update Cargo.lock files

* Apply suggestions from code review

Co-Authored-By: Bastian Köcher <[email protected]>

* Update core/service/src/chain_ops.rs

Co-Authored-By: Sergei Pepyakin <[email protected]>