apache.adduser can't be used for nginx unless apachectl is present

[ianheggie]

The apache module doesn't load unless apachectl is present, but that command isn't required for useradd (or userdel).

This would allow nginx only sites to use apache.adduser to maintain htpasswd files

Under ubuntu 12.04, apache2-utils package provides:

/usr/bin/ab
/usr/bin/checkgid
/usr/bin/fcgistarter
/usr/bin/htcacheclean
/usr/bin/htdbm
/usr/bin/htdigest
/usr/bin/htpasswd
/usr/bin/logresolve
/usr/bin/rotatelogs