dogfood own output

added `$ grunt upgrade` to move current ./task/ts.js to ./task/ts-internal.js

 ! only do this when stable !

renamed cloned task to 'ts-internal'
added 's-internal.js to .gitignore, .npmmgnore
changed `grunt build` to use 'ts-internal' to rebuild ./task/ts.js
keep ./task/ts.js to run the tests etc

dropped grunt-shell
dropped lingering unused module