Basic DHCP framework and DHCPCD proxies.

DHCPProvider singleton will instantiate and supply DHCPConfig objects. Each
DHCPConfig object corresponds to a separate DHCP client (dhcpcd). Each
DHCPConfig object will be associated with a single DHCPCDProxy object to
communicate with that client. DHCPProvider will use a DHCPCDListener singleton
to figure the D-Bus destination of each spawned DHCP client dispatch signals to
its DHCPCDProxy.

Also fix dhcpcd.xml (this needs to be fixed in dhcpcd itself, really).

BUG=chromium-os:16013
TEST=manual by modifying shill_main and instantiating the proxies.

Change-Id: I8fb0eadb8c751365997db2ed2bdfde0711c362a3
Reviewed-on: http://gerrit.chromium.org/gerrit/1934
Tested-by: Darin Petkov <petkov@chromium.org>
Reviewed-by: Darin Petkov <petkov@chromium.org>
13 files changed