Fix norway locales

[georgringer]

Instead of using no the following locales should be used:

• Norwegian Bokmål: nb_NO
• Norwegian Nynorsk: nn_NO

Both should have a fallback to no but should be fully localized.

Proposal

for v10:

• no: use it for nb_NO
• nn: add that as new locale

for v11

• drop no and rename it to nb

[georgringer]

from crowdin

The current “no” translation of TYPO3 is equal to “nb”, so the former can be imported into the latter without problem. (“no” is a code Kaspar invented; “nb” is the ISO equivalent.