Make gnt-node list-storage more standard
Make gnt-node list-storage more standard

This patch adds support for the -o+field,… format that the other list
commands accept and changes the format of the allocatable field from
simply str(bool) to Y/N.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>

bitemyapp/ganeti,ganeti/ganeti,bitemyapp/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,leshchevds/ganeti,ganeti/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,grnet/snf-ganeti,mbakke/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,dimara/ganeti,onponomarev/ganeti,yiannist/ganeti,dimara/ganeti,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,leshchevds/ganeti,ganeti/ganeti,mbakke/ganeti,apyrgio/snf-ganeti,apyrgio/ganeti,andir/ganeti,apyrgio/ganeti