Backend: Don't make temporary files to run the OCR, it's not required

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Backend: fix page scan

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Docsearch/cleanup: There is no temporary files for rotated image anymore --> no cleanup to do

Signed-off-by: Jerome Flesch <jflesch@gmail.com>