Add interrupt error kind

src/errors.rs

@@ -1,3 +1,5 @@
+use chan_signal::Signal;
+
 error_chain!{
     types {
         Error, ErrorKind, ResultExt, Result;
@@ -8,5 +10,10 @@ error_chain!{
             description("Connection error")
             display("Connection error: {}", msg)
         }
+
+        Interrupt(signal: Signal) {
+            description("Interruption by external signal")
+            display("Iterrupted by SIG{:?}", signal)
+        }
     }
 }