First release

The first release of php-sdb supports enough operations on SimpleDB that you can get stuff done, but you should probably wait a bit before using this in a production environment; error reporting is extremely minimal.

The current release is 0.4.0, and supports:
- listing, creating, and deleting domains
- getting, adding, and deleting attributes
- the 'Query' API endpoint

I've planned out the next several point releases and the next minor version increment, so development should go fairly quickly. Any feedback would be appreciated :)