Support datetime strings

[hvt]

Using the following (simple) query:

select * from test where time > '2013-01-01' limit 10

I get back an empty array while the log says:

********************************BUG********************************
Database: mydb
Query: [select * from test where time > '2013-01-01' limit 10]
Error: runtime error: invalid memory address or nil pointer dereference. Stacktrace: goroutine 30 [running]:
engine.func·004()
    /home/vagrant/influxdb/src/engine/engine.go:28 +0x116
datastore.(*LevelDbDatastore).sendBatch(0xc2000e8f90, 0xc2000e7d80, 0xc2001b68c0, 0xc2001b9760, 0x6c7800, ...)
    /home/vagrant/influxdb/src/datastore/leveldb_datastore.go:498 +0x136
datastore.(*LevelDbDatastore).executeQueryForSeries(0xc2000e8f90, 0xc2001bb776, 0x5, 0xc20015d1a0, 0x9, ...)
    /home/vagrant/influxdb/src/datastore/leveldb_datastore.go:462 +0x1200
datastore.(*LevelDbDatastore).ExecuteQuery(0xc2000e8f90, 0xc2000f55a0, 0xc200157ee0, 0xc2001bb776, 0x5, ...)
    /home/vagrant/influxdb/src/datastore/leveldb_datastore.go:216 +0x3bd
coordinator.(*CoordinatorImpl).DistributeQuery(0xc2000f77c0, 0xc2000f55a0, 0xc200157ee0, 0xc2001bb776, 0x5, ...)
    /home/vagrant/influxdb/src/coordinator/coordinator.go:29 +0x72
engine.(*QueryEngine).distributeQuery(0xc2000d0a90, 0xc2000f55a0, 0xc200157ee0, 0xc2001bb776, 0x5, ...)
    /home/vagrant/influxdb/src/engine/engine.go:61 +0x145
engine.(*QueryEngine).RunQuery(0xc2000d0a90, 0xc20

Note this fails without the 'limit'-clause too.

[jvshahid]

Thanks @hvt for reporting this issue. This feature isn't implemented yet. I'll try to get to it sometime today. Stay tuned.