Release 1.5 for Linux

Here are the changes we made the last weeks.

Added the ability to add site variables in the site.xml file directly
Added the ability to add page variables in the xml files. For example <Content language="en">
Slider editor now renders additional attributes like ("data-transition") which are not editable in plugin editor yet
Menuitems now supports additional attributes which are not editable in menu editor yet like class="scrollTo" which can be used as <a {{ item.attributes }} href=... in a theme
ImageEditor now supports additional attributes which are not editable in the plugin editor yet like data-animation="fadeIn" If an attribute with the class name is provided the original class will be overriden
Create wizard does now list all available themes