[FIX] Packaging: Debian: ignore root Makefile

Commit 388732dfa6a1 introduced a makefile at the root of the project, and
dh_auto_build is using this file instead of setup.py. Explicitely tell
debhelper to not use the makefile.
[FIX] point_of_sale: when loading models with a specified id, use read instead of search_read, to prevent inactive records from being skipped