Featurerequest: Waiting until the target index exists

[DagW]

When monstache starts synchronizing before the target index exists, it will be auto-created unless its turned off by elasticsearch cluster configuration.

It would be very nice to have monstache wait until the target index exists, since the dynamic-mapping can be very bad at guessing types.

Suggestion;
a new flag --wait-for-index index1,index2

[DagW]

Suggestion: #678 @rwynn

[yanqianglu]

+1 on the feature request, this will be very useful when using our own index mapping template.