imp(API): improved display of BadRequest

Previously you would only see "BadRequest ... " without the information
that would actually help you to understand what the cause of the issue
is.
Now we will print all the information we have, accordingly, which
greatly improves usability.

Closes #103
[skip ci]

src/rust/api/cmn.rs

@@ -291,8 +291,20 @@ impl Display for Error {
                 writeln!(f, "The application's API key was not found in the configuration").ok();
                 writeln!(f, "It is used as there are no Scopes defined for this method.")
             },
-            Error::BadRequest(ref err) 
-                => writeln!(f, "Bad Requst ({}): {}", err.error.code, err.error.message),
+            Error::BadRequest(ref err) => {
+                try!(writeln!(f, "Bad Requst ({}): {}", err.error.code, err.error.message));
+                for err in err.error.errors.iter() {
+                    try!(writeln!(f, "    {}: {}, {}{}", 
+                                            err.domain, 
+                                            err.message, 
+                                            err.reason,
+                                            match &err.location {
+                                                &Some(ref loc) => format!("@{}", loc),
+                                                &None => String::new(),
+                                            }));
+                }
+                Ok(())
+            },
             Error::MissingToken(ref err) =>
                 writeln!(f, "Token retrieval failed with error: {}", err),
             Error::Cancelled =>