TAP5-2209" Make JSONObject and JSONArray implement Serializable
TAP5-2202: t5/core/dom:ElementWrapper.attribute() should remove an element when setting its value to null
TAP5-2198: Palette should add the form-control class to its selects
TAP5-2188: Typo & Java Script error in Upload component / JavaScript module "injected-uploader.js"
TAP5-2227: Update Less4J to version 1.2.1 for compatibility with Bootstrap 3.0.2
Advance version number to 5.4-alpha-27