cleaned up HashValueJoin and added test
added namespace to perf_regression/HashValueJoin.cpp
minor fix to make merge easier
Move boost::uuid into wrapper class, improve build speed by 20%
Merge branch 'feature/cleanup_HashValueJoin' of https://github.com/timbokopter/hyrise into timbokopter-feature/cleanup_HashValueJoin

Conflicts:
	src/lib/access/HashValueJoin.hpp
Merge pull request #186 from bastih/timbokopter-feature/cleanup_HashValueJoin

HashValueJoin pr refresh
  * ValidatePositions can now be used with Stores
  * GroupByScan without Hashing for ops without grouping
  * Fixing bug in tablebuilder that would build a wrong layout, but correct view on top of it
  * Fixing default merge settings in Store, to not use compression
  * Made the code compiling without precompiled headers by including the necessary includes
Merge pull request #183 from bastih/feature/move_uuid_boost_to_single_compilation_unit

Move boost::uuid into wrapper class, improve build speed
Added benchmark_data to .gitignore
Merge pull request #176 from hyrise/feature/updates_to_querying_in_tx

Feature/updates to querying in tx
Added Metadata Operator with documentation and tests
Merge pull request #188 from irruputuncu/master

Added MetaData Operator with docs and test
tpccTableLoadTest.cpp now looks less copy-paste like
Merge pull request #190 from kateyy/tpccTableLoadTest

refactored TpccTableLoadTest
adding Operations to GroupByScan
* >as< to specify the name of the resulting aggregation column
* >min< and >max< as new operators
* >distinct< option for count operator (naive distinct algorithm)
* unit test for empty tables
Merge pull request #152 from lordgeorg/groupby_ops

adding Operations to GroupByScan
* >as< to specify the name of the resulting aggregation column
* >min< and >max< as new operators
* >distinct< option for count operator (naive distinct algorithm)
* unit test for empty tables
Fixing load performance issues
Adds minor MVCC improvements
* adds insert performance regression test
* MVCC: If a row is inserted and deleted in the same Tx, it is now invisible to the Tx (as it should be) - fixes #172
* Remove TXManager::getLastCID() calls from loop in Store::Merge #181
* TXManager::commitTransaction should get complete context instead of commit id only - changed rollback as well #181
Merge pull request #196 from hyrise/feature/load_fix

Fixing load performance issues
Merge pull request #194 from hyrise/feature/new_mvcc

Adds minor MVCC updates