Remove unnecessary join against releases table

This gets rid of the warning:

  DBIx::Class::Storage::DBI::select_single(): Query returned more than one row.  SQL that returns multiple rows is DEPRECATED for ->find and ->single at /home/eelco/Dev/hydra/src/script/../lib/Hydra/Controller/Project.pm line 15
Handle utf-8 properly

Fixes errors like:

  Caught exception in engine "Wide character in syswrite at /nix/store/498lwsrn5kkdh1q8kn3vcpd3457w6m7a-hydra-perl-deps/lib/perl5/site_perl/5.16.3/Starman/Server.pm line 547."

Note that these errors didn't happen if the database encoding was set
to SQL_ASCII (which was the case for hydra.nixos.org, explaining why
it didn't get these errors). However, now the encoding must be
UTF8. To change it, do:

  update pg_database set encoding = pg_char_to_encoding('UTF8') where datname = 'hydra';