simplify rake test vs rake test:all

Remove rake test:all and replace rake test with former definition of rake test:all.  Also rename rake test:all:db to rake test:db
This changes default test behavior to run everything, which may now include e.g. acceptance/browser/system tests.

For behavior parity, we'd use a tighter glob, or introduce config so people can specify which tests dirs to include by default.

```
t.pattern = "test/{units,models,etc}/**/*_test.rb"
```