DRY up the specs by moving into an each loop

This moves all the common attributes into a loop for different versions. If you wanted to go really hardcore on coverage, you could change the array into something like:

```
versions = Array ('1.6.0'..'1.7.11')
```

So you'd get this set of specs for every version in between, but I thought this was a little overkill...
Rename exec, move command to command parameter

Easier to figure out what the exec is doing, and makes the specs a little nicer.
Specs are now green...but...

It looks like the specs weren't updated when a few things changed, such as the lack of creates in the install exec. This gets things green, but I'm not sure if the manifest is actually right...
Merge pull request #35 from petems/fix_subtree_spec

Fix subtree spec