Add option for loading serialized instances
Add option for loading serialized instances

Monitoring CLI tools might have to load serialized lists of instances
(mainly for testing reasons). This patch adds an option to allow that.

Signed-off-by: Michele Tartara <05f7077a2c6cbbdc4af4ba42e3ef89a0df846179@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

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