[FIX] base: incorrect code and locale for Bosnian

Stems from prebiblical commit f083aa2.

Fixes #3480
[IMP] *: one Makefile to rules them all.

Create one unique generic Makefile to compile sass files.
[MERGE] forward port of branch 7.0 up to 65d92da
[FIX] web,web_kanban: correct radial-gradient usage
[MERGE] forward port of branch 7.0 up to 3e3e35e