Fix DSL/mock specs up to run, reveals a number of SWT failures though...

There was one failure:

```
1) Shoes::App#append understands append
Failure/Error: subject { Shoes::App.new(opts, &input_blk) }
NoMethodError:
undefined method `contents_alignment' for #<Shoes::Mock::Para:0x24c39565>
# ./lib/shoes/text_block.rb:93:in `contents_alignment'
# ./lib/shoes/slot.rb:96:in `positioning'
# ./lib/shoes/slot.rb:88:in `position_contents'
# ./lib/shoes/slot.rb:86:in `position_contents'
# ./lib/shoes/slot.rb:65:in `contents_alignment'
# ./lib/shoes/slot.rb:19:in `initialize'
# ./lib/shoes/app.rb:144:in `eval_block'
# ./lib/shoes/app.rb:42:in `initialize'
# ./spec/shoes/app_spec.rb:6:in `subject'
# ./spec/shoes/app_spec.rb:184:in `(root)'
```

There are like 24 specs though that fail o the SWT end related to methods not being called.

Thanks and cheers!
Tobi