logging in contract and non contract env

[ple1n]

No description provided.

[iduartgomez]

fails in tests:

error[E0433]: failed to resolve: could not find `freenet_stdlib` in the list of imported crates
  --> rust/src/log.rs:7:11
   |
7  |         ::freenet_stdlib::log::info(&format!($($arg)*));
   |           ^^^^^^^^^^^^^^ could not find `freenet_stdlib` in the list of imported crates
...
31 |     info!("n={}, y={:?}", 1, 2);
   |     --------------------------- in this macro invocation
   |
   = note: this error originates in the macro `info` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider importing this module
   |
1  + use crate::log;

need to use relative import from crate