Add output destination option to build command

Simple support for an output destination on `build` command via `--destination` and alias `-d`.
Supports both absolute and relative paths, including nested directories e.g.

```
 $ ipa build -d foo # => ./foo
 $ ipa build -d foo/bar # => ./foo/bar
 $ ipa build -d /tmp/foo # => /tmp/foo
```

Creates the destination if it doesn't already exist.

Backwards compatible with current `build` behaviour but no integration with `distribute` command.