Person: update result message

There are no delimiters between each field entered and an additional
phrase 'Tags:' is always present even if the user did not input any
tags.

As a result, the result message is not as user-friendly.

Let's add delimiters and remove 'Tags:' from the result message if tags
are not present.

src/main/java/seedu/address/model/person/Person.java

@@ -106,13 +106,16 @@ public int hashCode() {
     public String toString() {
         final StringBuilder builder = new StringBuilder();
         builder.append(getName())
-                .append(" Phone: ")
+                .append("; Phone: ")
                 .append(getPhone())
-                .append(" Email: ")
+                .append("; Email: ")
                 .append(getEmail())
-                .append(" Address: ")
-                .append(getAddress())
-                .append(" Tags: ");
+                .append("; Address: ")
+                .append(getAddress());
+
+        if (getTags().size() > 0) {
+            builder.append("; Tags: ");
+        }
         getTags().forEach(builder::append);
         return builder.toString();
     }