Adds lots and lots of namespaces ... and some related things:

* more pragma once
* more auto (where namespaces would just have to been verbosely written)
* some lines removed (if obviously unnesessary and namespaces would have to be
   applyed)
* removed some now unnessesary namesapce references (mostly "hyrise::")
Merge pull request #272 from lordgeorg/namespaces

More consequent namesapces in hyrise