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
Making GroupBy value aware
Partially revert 65bc666

* Removes accidental changes from earlier commit
Add basic server testing to ci tests
Merge pull request #197 from bastih/master

Partial revert, add server tests for CI
Remove unused variable
Prevent dangling else-warning
Fix warning in groupby tests
Add a meaningful message for join types
Modernize JoinScan
Merge pull request #202 from bastih/master

Some small cleanups
Adding missing test and docs
Merge pull request #204 from hyrise/feature/groupby_doc_test_fix

Adding tests and docs