Partial merge of efforts including:

* Several new index implementations
* Buffered Logger recovery (compile time parameter)
* Grouped commits
Read-write lock for DeltaIndex
Reinstated layouter tests
Reformat
Undo makefile tweaks
Remove changes from obsolete file
Remove NVRAM-remnants
Merge pull request #333 from hyrise/feature/index_recovery_persistency

features: indexes, recovery, persistency