Making Sync Feature the Default Feature

Making sync feature the default feature even though it is less
performant to make the user experience simpler. See issue 176.

Author: sccalabr

Cargo.toml

@@ -24,7 +24,7 @@ wasm-bindgen = "0.2"
 wasm-bindgen-futures = "0.4"
 
 [features]
-default = ["isahc-static-curl"]
+default = ["isahc-static-curl", "sync"]
 isahc-static-curl = ["isahc/static-curl"]
 sync = []