make modeladmin preview work in SilverStripe 4 

disable cache in preview 

v2 

Fix typo 

Merge pull request #2 from dnadesign/fix_render_easier_override added special method for rendering, so that it’s easier to override

fix hiding of mode selector in dataobject preview pane when switching… … to content

update on CMSEditLink, first param is ClassName, second ID 

add installer-name 

first release