Check for index blocks against concrete indices on master operations

[javanna]

Some master operations require to check for index blocks, done by overriding TransportMasterNodeOperationAction#checkBlock. We need to make sure though that the check is done against concrete indices, otherwise we might not get blocks back altough there are.

For instance you can currently delete a read-only index using an alias that points to it, or using the _all alias:

curl -XPUT localhost:9200/foo

curl -XPUT 'localhost:9200/foo/_settings' -d '
{
    "index" : {
        "blocks.read_only" : true
    } }
'

curl -XDELETE localhost:9200/foo
#{"error":"ClusterBlockException[blocked by: [FORBIDDEN/5/index read-only (api)];]","status":403}

curl -XDELETE localhost:9200/_all
#{"acknowledged":true}

The problem seems to affect the following apis:

• delete index
• delete mapping
• types exists
• indices exists
• open index
• close index