Update database_cleaner and rake

- database_cleaner to 1.2.0 (was 0.7.1)
- rake to 10.1.1 (was 10.1.0)
Remove dead code
Move sync_all and sync_delta out of SyncTable class

When properly requiring files it would throw an error because SyncTable
is a class, not a module
Properly require files in spec_helper
Fix require sync in sync_table spec
Move sync_all_tables to Switch

`sync_all_tables` used to take a switch as argument, why not moving it
to the switch directly ?