grapher: Quality commit

Fixing stylish issue from models
grapher: Allow non-string items

When computing some values, grapher considered that everything was a
string while some where integers.

This patch insures that everything is turned into string.
detect & health-check: All values as string

Insure that all values as set as string to keep a consistency across
values.

This could be useful also for grapher to estimate that everything is the
same.