monitor: Deviation attribute details(docs) & enforce range

The `deviation` attribute contains the +/- percentage allowed for the
sensors to deviate from any requested target.

Also enforcing the `deviation` value provided in the JSON configuration
is between 0 and 100.

Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
Change-Id: I3064e9b407c2edec7fb0fd36a2d1cd3f53d3e397
2 files changed