red: change BauPack to be a task builder
green: change BauPack to be a task builder
#27 red: added Bau.Test.Acceptance/Plugins/Exec
immunised tests against System.IO and file system race conditions
#27 green: implemented Bau.Test.Acceptance/Plugins/Exec
#27 refactor: rationalised inheritance graph and added BauPackFacts
#27 refactor: renamed TaskBuilder to BauPack
refactor: removed redundant TODOs and made Task.Execute public
#27 refactor: split ExecTask into separate plugin
Merge pull request #32 from adamralph/27

#27 exec plugin