I experimented a bit.
When I do not import directly into Aperture, but use Image Capture to import, you will see, that all image files come accompanied by a .AAE sidecar file. The image files are now stored on the iPhone as pairs, the JPEG and an sidecar file with metadata and adjustments. Image Capture in Yosemite imports the image files in pairs, so the edits can be applied loosely. We only need to find an image editor, that can read .AAE.
After importing from my iPhone with Image Capture the folder will show for example:
IMG_1416.AAE IMG_1416.JPG IMG_1488.AAE IMG_1488.JPG
Opening one of the .AAE files in TextEdit I can see that the adjustments are inside:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>adjustmentBaseVersion</key>
<integer>0</integer>
<key>adjustmentData</key>
<data>
bY2xCsIwFEX/5c4ZtBaRrCI4OdpBHJ7mpX1iEkhep9J/N2rBxe1yONwzwaccSM+ci6QI
uzYIrORICXZCoKKcjyz9oLBN2+7MwjpxOsBumm1rkLJwVNLvxWxA7jEWDRUW2Mv0p8KR
bk92sJpHNiisKrEv7yh7z/efvDILOVFgWOyHnOqoFXE1IF44V3z4OJiv8ws=
</data>
<key>adjustmentEditorBundleID</key>
<string>com.apple.camera</string>
<key>adjustmentFormatIdentifier</key>
<string>com.apple.photo</string>
<key>adjustmentFormatVersion</key>
<string>1.0</string>
</dict>
</plist>
Aperture, iPhoto, Preview ignore this file. I hope, this will change.