Fixed random database directory name generation
Fixed random database directory name generation

Without seeding, subsequent calls to rand.Int() return 
the same sequence of numbers every time the program is run.
influxdb/hyperleveldb-go,jmhodges/levigo,chanxuehong/goleveldb,influxdb/levigo,evanphx/levigo,DanielMorsing/rocksdb,alberts/gorocks,mikefaille/rocksdb-go,elijahandrews/levigo,jmhodges/levigo_leveldb_1.4,dckit/rocksdb,influxdata/rocksdb,influxdata/hyperleveldb-go,influxdb/rocksdb