add logs for flaky multipart test

.travis.yml

@@ -32,4 +32,4 @@ cache:
 
 script:
   - cargo build $FEATURES
-  - cargo test -v $FEATURES
+  - RUST_LOG=hyper,reqwest cargo test -v $FEATURES

tests/multipart.rs

@@ -1,3 +1,4 @@
+extern crate env_logger;
 extern crate reqwest;
 
 #[macro_use]
@@ -5,6 +6,8 @@ mod support;
 
 #[test]
 fn test_multipart() {
+    let _ = env_logger::init();
+
     let form = reqwest::multipart::Form::new()
         .text("foo", "bar");