Merge pull request #6802 from mvdbeek/fix_int_parsing_rules

[18.05] Cast rule.length to int when parsing rules

client/galaxy/scripts/mvc/rules/rule-definitions.js

@@ -297,7 +297,7 @@ const RULES = {
         },
         save: (component, rule) => {
             rule.target_column = component.addColumnSubstrTarget;
-            rule.length = component.addColumnSubstrLength;
+            rule.length = parseInt(component.addColumnSubstrLength);
             rule.substr_type = component.addColumnSubstrType;
         },
         apply: (rule, data, sources, columns) => {