Updated SnakStore interface to use StoreSnak data structure

Change-Id: I2f308c2fd89b921feb0457af1ff0fa7046d13e73
Removed unused imports

Change-Id: Ib302d3aa4faa6ba559a781e12ffb7445eab2ca43
Rename StoreSnak to SnakRow

Change-Id: Ie7378a580b567ec4aa35aa6b520eaf762f5e01ae
Renamed SnakStore->storeSnak to SnakStore->storeSnakRow

Change-Id: I1ad0e6ac95bfd4d569b264b9f747fc57e460549b
Implemented NoValueSnakStore->storeSnakRow

Change-Id: Ie2467d72ce616b3a26bd46c83bb8187db5e2918b
Update field names of valueless snaks table for clarity

Change-Id: Icbb21368ae146460b34f51616a2bf17184055dc3