* Add deleteMeasurement to store and shard
* Add DropMeasurement to DatabaseIndex
* Update ErrMeasurementNotFound and ErrDatabaseNotFound to not include the first line of the stack trace.
* Pulled over updates to ast and parser from master
* Updated store and shard to be able to drop series
* Pulled updates to database.go from master into tsdb/meta.go
Fixes issue where queries wouldn't be able to hit anything because the index does't load until the shard is open.
Fix an issue where field codecs weren't populated in the shard when loading.
Uses a structure like:
/root/
/db1/rp1/1
/2
/db2/rp2/3
If a write is assigned to a shard on the local node but the shard
has not been created, create it when the write returns an error
and retry the write.