Collapse Kernel.TransactionImplementation into KernelTransactionImplementation.

o In order to make Transactor testable we have removed the MicroTransaction
   execution concern form KernelTransaction. To do this we had to expose some
   more schema operations from Statement.
Merge pull request #1235 from benbc/2.0-KernelTransaction-hierarchy-collapse

Collapse Kernel.TransactionImplementation into KernelTransactionImplemen...
Replace IndexProxy.{update|recover} with IndexProxy.newUpdater(mode)

o Temporarily @Ignore RuleUpdateFilteringIndexProxyTest
Split out the concurrent map from IndexingService

o Abstracts how that map is updated and also what mappings are tracked internally
o This prepares for having multiple mappings instead of only being able to lookup by long