implement transaction expiration limits
transaction expiration, and optional scanning

Transactions now set a default expiration
There is now a wallet option to enable scanning for the purposes of unit
tests.
updating unit tests for scanning
Remove testing shim from wallet_unlock

Accidentally left some code in that forces a rescan. Sorry, all!
Fix Delegate loop scheduling bug that was hanging up titan test. Also changed ntp_time to return microseconds instead of a double to simplify and speed up the code a bit.
Limit total size of queued messages for p2p nodes (currently 1MB).
Add exception types for bts::net.
Re-enable and fix compile errors in bitshares_client_tests.
Quiet a few compiler warnings
implemented ability to upgrade to a delegate and reduce your pay
updating genesis block timestamp
reducing desired connection count to 8
adjust max block size to yield about 2 trx/sec maximum
in-memory cache of known transaction IDs used to accelerate validation
Wallet now uses fc::schedule for relocking (resolves #358)
fix conflicts
Merge branch 'master' of github.com:BitShares/bitshares_toolkit

Conflicts:
	libraries/blockchain/include/bts/blockchain/time.hpp
updating fc
Fix wallet relocking
Merge branch 'master' of github.com:BitShares/bitshares_toolkit
adding extra peer
Merge branch 'master' of github.com:BitShares/bitshares_toolkit
Fix wallet_create and wallet_close (resolves #436)