Rethink normalization

The whole normalization approach might not be as feasible as thought if
it is applied before displaying the results on the view. I think the
normalization has to be done right after the metric has been computed.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Cap accessibility metric to avoid normalization

The accessibility metric is also pretty normalized. The only thing
required, is to cap the range of possible values to [0, 100]. This
way the Flesch index only needs to be divided by 100.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>