Added DNS resolution to AWS settings lookup

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>
Fixed go agent run script to provide infrastructure flag -I

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>
Updated go agent dns resolver not to try and resolve IPs

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>
Fixed parsing of settings from bosh registry

Signed-off-by: Damien Le Berrigaud <damien@pivotallabs.com>