Merge pull request #23 from dthorpe/master

Tell git to ignore the nuget packages build subdir
rename ITransactionMonitor to IChainStateMonitor
fleshing out IChainStateMonitor
rename ChainedBlock to be ChainedHeader and add in full header information, eventually the storage of ChainedHeader and BlockHeader can be combined, #13
rename utxo builder as chainstate builder and include the current block hash, the block processing and validation will be moved
move block hash updates inside chain state transaction, the builder no longer needs to be discarded on an exception
fix block hash update
add pruning mode to remove utxo spent information only, turn pruner back on
add ChainedBlock akin to ChainedHeader
rename UtxoStorage to be ChainStateStorage
finished todo note
add immutable snapshots back to chain state builder, cleanup
turn off output indexing for now
organizing the code between the chain state builder and worker
remove DisposeDelete, todo note
organize chain state builder methods, split out revalidate code into a worker
cleanup worker shutdown
typo
rename IChainStateMonitor to IChainStateVisitor
add ChainStateMonitor for subscribing