Remove unused index stats for MemoryTable
fixed bug in Export set, fifth argument now correctly determines the number of bits returned
Concurrent insert+statistics test
indexIterator gets another boolean for snapshot
TableStatus#getApproximateRowCount gets Session paramter.

Use getApproximate when computing statistics.

Use snapshot read for FDB getApproximate.
Use snapshot range scan for index statistics traversal
Updated behaviour for negative values of the fifth input argurment, similar to mysql
merge SytzeH: Bug fix in MExportSet

Merge pull request #1263 from SytzeH/sql-layer/expSet
https://github.com/FoundationDB/sql-layer/pull/1263
Add a call to wrapFDBException() in two more placess from which it was
missing.
Transaction required
merge nathanlws: Snapshot reads for statistics generation

Merge pull request #1264 from nathanlws/sql-layer/stats-are-snapshot
https://github.com/FoundationDB/sql-layer/pull/1264
Move the call FDBAdapter.wrapFDBException up a level on the stack, to
ensure any call to FDBTransactionState also does not let FDBException
leak through.
Larger refactoring of the FDBTransactionService and it's users. Remove
most (but not all) uses of TansactionState.getTransaction() so the
internal use of the FDB Transaction can be managed (and errors properly
handled).
Merge remote-tracking branch 'github/master' into
catch-fdb-exception-commit-periodic

Conflicts:
	src/main/java/com/foundationdb/server/FDBTableStatusCache.java
	src/main/java/com/foundationdb/server/store/format/FDBStorageDescription.java
ALTER TABLE ADD INDEX idindex(id) is now supported, as is ALTER TABLE c ADD CONSTRAINT indexConstrName INDEX indexName(id)
minor changes to undo auto imports
merge SytzeH: Support for: Alter table add index

Merge pull request #1267 from SytzeH/sql-layer/alterTableDI
https://github.com/FoundationDB/sql-layer/pull/1267
Add try/wrap/throw to the FDBStoreDataIterator implementations to ensure
exceptions are processed correctly. 

Clean up a few imports as well.
Add more processing to the TransactionState, refactoring in a few calls
to get<stuff> which wanted only to wait for the results. Pull these into
the TransactionState and add try/wrap/throw
fix all the calls to Future.get() with try/wrap/throw by having them all
go back through the base PendingCheck<> class.