[core] bump version number -> 2.5.3 (prepare future release)
[pkg] fix makefile for the case of 2 modules sharing a same prefix

eg. drawgantt & drawgantt-svg
or kamelot & kamelot-pg
[pkg] Rename draw-gantt module -> drawgantt
[visualization] add packaging for drawgantt-svg
[pkg] add oar_sched_gantt_with_timesharing_and_placeholder
[visualization] Add PostgreSQL support to drawgantt-svg
[visualisation] drawgantt-svg: rework the configuration settings
CGROUP: handle cgroup hierarchy already mounted by the OS like in Fedora 18
        (by systemd in /sys/fs/cgroup) in job_resource_manager_cgroups.pl
[pkg] fix drawgantt-svg setup
[database] fix mysql reset SQL

Table schema must be backquoted... -> `schema`, hence backquoting every
tables
[misc] update CHANGELOG
[visualization] fix default config for monika (close #12294)
[tools] Add the command "oar_resources_init_with_HT" wich generates right
        resources to add in the DB with a "thread" property (HyperThreading)
[tools] make detect_resource handle the fact that oarnodes may not be available

+ rework esthetic
[pkg] add SELinux checks to oar-server and oar-node init scripts + cosmetic fixes
[oarsub] fix stdout/stderr bug: check the allowed characters in the path given by the users
[oarexec] the user shell (bash) didn't source /etc/bash.bashrc in batch jobs
[pkg] fix oar-node init script
Added stress_factor into changelog
[CHANDLER] Minor cosmetic change (justify)