Fix content-manager offset for SQL databases

packages/strapi-bookshelf/package.json

@@ -55,4 +55,4 @@
     "npm": ">= 5.3.0"
   },
   "license": "MIT"
-}
+}

packages/strapi-knex/package.json

@@ -46,4 +46,4 @@
     "npm": ">= 5.0.0"
   },
   "license": "MIT"
-}
+}

packages/strapi-plugin-content-manager/config/queries/bookshelf.js

@@ -11,9 +11,9 @@ module.exports = {
         qb.orderBy(params.sort);
       }
 
-      qb.offset(params.skip);
+      qb.offset(_.toNumber(params.skip));
 
-      qb.limit(params.limit);
+      qb.limit(_.toNumber(params.limit));
     }).fetchAll({
       withRelated: this.associations.map(x => x.alias)
     });