Bumb version number to 0.5.0

package-lock.json

 {
   "name": "@logilab/libview",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

 {
   "name": "@logilab/libview",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "Library for view specification and definition for a data browser.",
   "scripts": {
     "clean": "rm -rf build",