Set RUST_LOG environment var for all examples using tracing (#123)

* Set RUST_LOG environment var for all examples using tracing

Signed-off-by: Spencer Gilbert <[email protected]>

* Update examples/multipart_form.rs

Co-authored-by: David Pedersen <[email protected]>

examples/sessions.rs

@@ -20,7 +20,13 @@ use uuid::Uuid;
 
 #[tokio::main]
 async fn main() {
-    tracing_subscriber::fmt::init();
+    // Set the RUST_LOG, if it hasn't been explicitly defined
+    if std::env::var("RUST_LOG").is_err() {
+        std::env::set_var("RUST_LOG", "sessions=debug")
+    }
+    tracing_subscriber::fmt::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .init();
 
     // `MemoryStore` just used as an example. Don't use this in production.
     let store = MemoryStore::new();