Version bump
Make drop_everything() independent of individual drops
drop_tables() also needs to drop indexes & triggers
Remove unecessary subtest() calls in tests
Set release date
Revert "Set release date"

This reverts commit 9be6be26701bfbcace563709174f1811270544af.
Bump VERSION to 0.0.18
Add .swp to MANIFEST.SKIP
Set release date 2014-04-10
Merge tag '0.0.18'