Wallet Light Client Compiles

Added light_api for server, just stubs right now.
Resolved various compile issues in light wallet.
Update Mac build instructions
Making relay fee configurable via config.json
Update Mac build instructions
Market Engine: Index Collateral Orders by Expire

- the market engine was scanning all collateral orders every time the
market engine exeuted which created a DOS vulnerability if someone were
to create a large number of small short positions.  This commit creates
an index that effeciently finds only the expired orders.
Update README; #1100
adding TODO for tests that need to be implemented
update webwallet to head
[GS]Update regression tests
revert restricted uia test
#1118 moved mail delete test to features/mail_removal.feature
Unrevert fc
Fix slow wallet scanning in production
Allow regenerating keys for inconsistent account records
Improve syncing of local wallet accounts with blockchain
Minor wallet scanning cleanup
Revert filtering by withdraw condition for wallet_account_balance{_ids}
Allow trading higher MIAs with lower UIAs; #949
Update web_wallet submodule
Merge branch 'develop' into bitshares