Merge pull request #123 from bastih/master

Add /operations/ url endpoint for listing registered Ops
Reorganizing Repository

More Reorganizing Files for better sight :)
Merge pull request #124 from hyrise/feature/reorg_access_lib

Feature/reorg access lib
Adding Fix for the Broken Build and A new Generic Expression for 3 Fields
Broken Build
Meta Expressions

Defining expression for the TableScan using a single line of code (maybe 2)
Merge pull request #126 from hyrise/feature/macro_expressions

Meta Expressions