update <header> content (see message)
-change ".gl-header" class on <header> to ".gl-header-logo"
-add an <hr> tag with a ".gl-hr" classname
-add an <h2> tag
update <header> related classes (see message)
-rename ".gl-header" class to ".gl-header-logo" in "globals.less"
-add ".gl-hr" class ro "globals.less"
-build out core css files