Support separate web/db servers.

[mikelococo]

Provide separate recipes for the apache and mysql stuff and add attributes that would allow folks to use a separate web and database servers.

@piratenfraktion-nrw has done some work in this direction, but hasn't separated the recipes: piratenfraktion-nrw@fbd89e4

@mikelococo runs his own servers on a single web/db node, so may or may not pick this enhancement up. PR's in this direction would be gladly reviewed, though.