Integration tests

[RCasatta]

With this by default cargo test will not print any logs

by doing RUST_LOG=debug cargo test instead, there is the same logging than before this MR

[shesek]

I'm fine making this change, but just curious - what's the rational behind it?

[RCasatta]

The rational is that by default cargo test should not print anything but the test results summary.

For example running on master you have:

running 2 tests
test rest::tests::test_parse_query_param ... ok
test rest::tests::test_parse_value_param ... ok

... a lot of log lines ...

test test_rest ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 2.45s

So to see test_parse_query_param result you have to scroll up, and for some refactor those these stop to be executed you risk to miss it