Feature/cache improvements 2 (#1067)

* New Mode to control queryCache behavior

* Collections form the cache have to be read only

* findCount not queried in query cache

* return modifiable collections from the cache

* FIX: Compile errors

* No effective code change: reformat code / javadoc

src/main/java/io/ebeaninternal/server/expression/JunctionExpression.java

@@ -742,7 +742,7 @@ class JunctionExpression<T> implements SpiJunction<T>, SpiExpression, Expression
   }
 
   @Override
-  public Query<T> setUseQueryCache(boolean useCache) {
+  public Query<T> setUseQueryCache(CacheMode useCache) {
     return exprList.setUseQueryCache(useCache);
   }