asn: changed blob named asn/approved to asn/approvals

to be consistent with asn/removals

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: clarify permissions

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: update mark

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: introduce BLOB reference argument

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: remove scan command

believe we can achieve same functionality more efficiently with,

	cat SERVICE/asn/mark@EPOCH

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: add -u flag to disambiguate USER argument

Signed-off-by: Tom Grennan <tom@apptimist.co>
asn: ack with blob sum

Signed-off-by: Tom Grennan <tom@apptimist.co>