On some workloads, a process creating backups should not become so
aggressive on resources that it prevents normal activity of a machine
from running. It is especially important when writing to disk.
One way to make backups have less impact on the main workload is to
force backups to a lower ionice level.
With the new ionicelevel configuration, it becomes possible for users to
activate the use of ionice and to define the level within the
best-effort class to better suit their needs.
Previously, there were many indentation styles in use: Real tabs, 2, 3
or 4 spaces, mixing these within the same file, function or even within
a single line.
This commit changes all bash scripts in the handlers, src and lib dirs
to use consistent indentation: three spaces are now used everywhere.
Other files (e.g. Makefiles) are left untouched.
Additionally, this commit removes all trailing whitespace.
