Add default theme for maalr

The default theme is defined in default.css
Update login.jsp, add social sign in images
Add a template page

Add a template page for optional content
Remove misplaced @include statements

Remove misplaced @include statements for login_widget.jsp and
language_widget.jsp. The widgets are already included through header.jsp
Include link to template.jsp

Include link to template.jsp, shift @include statement for
login_widget.jsp
Add the Apache commons-lang3 lib

The lib is used to escape html