add code & testing files for continue-on-error flag

- add continue-on-error flag as a command line option
    - if set, doesnt exit on error and continues
        processing other files that were passed in
- add fatalErrorHandler to handle fatal errors
    - if continue-on-error flag is set, does not exit
- add temporary tests for continue-on-error flag
    - add tests in batch-tests subdirectory

error_handler.go

@@ -0,0 +1,35 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/reconquest/pkg/log"
+)
+
+type FatalErrorHandler struct {
+    ContinueOnError bool
+}
+
+func NewErrorHandler(continueOnError bool) *FatalErrorHandler {
+    return &FatalErrorHandler{
+        ContinueOnError: continueOnError,
+    }
+}
+
+func (h *FatalErrorHandler) Handle(err error, format string, args ...interface{}) {
+	errorMesage := fmt.Sprintf(format, args...)
+
+    if err == nil {	
+		if h.ContinueOnError {	
+			log.Error(errorMesage)
+			return
+		}
+		log.Fatal(errorMesage)
+    }
+    
+    if h.ContinueOnError { 
+        log.Errorf(err, errorMesage)
+		return
+    }
+    log.Fatalf(err, errorMesage)
+}