utilities for http operations and link parsing

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>
a simple url getter and link parser actor

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>
turning Getter into a per request actor, and adding a Controller actor to cache results

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>
retrieving links of links, where the depth of this is encoded as a parameter; a new, Receptionist actor starts Controllers per url

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>
using deathwatch to manage children

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>
Receptionist supervises its Controller children

Signed-off-by: Mikolaj Szabo <savingprivateblue@gmail.com>