Fix panicking when passed a file:// URL

Closes #347

src/proxy.rs

@@ -49,7 +49,7 @@ impl Proxy {
     /// # fn main() {}
     /// ```
     pub fn http<U: IntoUrl>(url: U) -> ::Result<Proxy> {
-        let uri = ::into_url::to_uri(&try_!(url.into_url()));
+        let uri = ::into_url::to_uri(&url.into_url()?);
         Ok(Proxy::new(Intercept::Http(uri)))
     }
 
@@ -68,7 +68,7 @@ impl Proxy {
     /// # fn main() {}
     /// ```
     pub fn https<U: IntoUrl>(url: U) -> ::Result<Proxy> {
-        let uri = ::into_url::to_uri(&try_!(url.into_url()));
+        let uri = ::into_url::to_uri(&url.into_url()?);
         Ok(Proxy::new(Intercept::Https(uri)))
     }
 
@@ -87,7 +87,7 @@ impl Proxy {
     /// # fn main() {}
     /// ```
     pub fn all<U: IntoUrl>(url: U) -> ::Result<Proxy> {
-        let uri = ::into_url::to_uri(&try_!(url.into_url()));
+        let uri = ::into_url::to_uri(&url.into_url()?);
         Ok(Proxy::new(Intercept::All(uri)))
     }