Update list of locales

Fix issue #141

Locales removed from all branches (never received an update from 2008,
when we switched from CVS to Hg): ne-NP, nr, ss, st, ts, ve.

Locales added: az, mn, sah, ur (only mn exists on l10n-central).
Locases removed from central: ff, lij (empty repositories).

Remove ff, lij from central.txt (empty repository)
Merge pull request #142 from flodolo/update_sources

Update list of locales