update translations; add: da, id, ko, sr, sv

Signed-off-by: Chris Warrick <kwpolska@gmail.com>
add ar translation

Signed-off-by: Chris Warrick <kwpolska@gmail.com>
pygal==1.6.0

Signed-off-by: Chris Warrick <kwpolska@gmail.com>
Merge branch 'master' of https://github.com/getnikola/nikola