Gemfile cleanup, `gem 'sass', '3.4.1'` issue #24
views: `login.haml` adapt to new css
controller: `system` require Prawn dependencies, fix #22
models: `Trst::Page` slug nil issue (todo ???)
lib: `trst_helper` button, buttonset, fix #23
assets: js, use FontAwasome by default, for buttons issue #20
assets: css, updated
views: `system` default CRUD, use new `button|td_buttonset` help
update CHANGELOG
update CHANGELOG
Merge branch 'feature/v0.2.996' into develop