changed UITableViews to be opaque

Signed-off-by: Ralph Samer <ralph.samer@student.tugraz.at>
fixed #90 and #91 (lill' workaround hack)

Signed-off-by: Ralph Samer <ralph.samer@student.tugraz.at>
@fix #90 and #91: minor change to viewDidAppear

Signed-off-by: Ralph Samer <ralph.samer@student.tugraz.at>
improved hack to use dynamic sizes

Signed-off-by: Ralph Samer <ralph.samer@student.tugraz.at>
fixed performance problem for importing images + creating thumbnails now

copying image from UIImagePickerController to disk is now performed on other thread, UI updates of course on main thread

Signed-off-by: Ralph Samer <ralph.samer@student.tugraz.at>