add svg and other mime types to file extension detection (#189)
add svg and other mime types to file extension detection (#189)


google/playground-elements,PolymerLabs/code-sample-editor,google/playground-elements,PolymerLabs/code-sample-editor,PolymerLabs/code-sample-editor,PolymerLabs/code-sample-editor-package,PolymerLabs/code-sample-editor-package,PolymerLabs/playground-elements,PolymerLabs/playground-elements,google/playground-elements,PolymerLabs/playground-elements,PolymerLabs/code-sample-editor-package