Remove 'data' directory

[apavlo]

I think we can safely remove these files.

[bpkroth]

Currently some of the twitter tests are marked as @Ignore in part because of some NullException errors due to the tracefile xmlConfig references.
It would be nice if this PR could also enable those tests again as a part of this change.

See Also:

benchbase/src/test/java/com/oltpbenchmark/benchmarks/twitter/TestTwitterLoader.java

Line 25 in 494781c

@Ignore("the testcase is under development")

benchbase/src/test/java/com/oltpbenchmark/benchmarks/twitter/TestTwitterWorker.java

Line 9 in 494781c

@Ignore("the testcase is under development")

[bpkroth]

The templated benchmark has an example config in the data directory right btw.