Added toString methods to new cert classes

src/uk/co/md87/evetool/api/wrappers/data/CertCategory.java

         return name;
     }
 
+    @Override
+    public String toString() {
+        return "[" + name + ": " + classes + "]";
+    }
+
 }

src/uk/co/md87/evetool/api/wrappers/data/CertClass.java

         return name;
     }
 
+    @Override
+    public String toString() {
+        return "[" + name + ": " + certificates + "]";
+    }
+
 }

src/uk/co/md87/evetool/api/wrappers/data/CertInfo.java

         return skillReqs;
     }
 
+    @Override
+    public String toString() {
+        return "[" + id + ": grade " + grade + "]";
+    }
+
 }