Merge pull request #3 from monero-project/master

Syncing with official bitmonero
Merge pull request #4 from monero-project/master

Pull monero-project changes
Merge pull request #5 from monero-project/master

Pull monero-project changes
Merge pull request #6 from mikezackles/arch_linux_build_fixes

Arch linux build fixes
Added minimum fee error message in 'transfer' RPC call
High level library draft for Wallets : Open, Generate
More methods
Added refresh and first 'transfer' method. Wallet observer draft
Refactoring + Moar methods + some doc
Added 'get_payments'
Added 'on_payment_received' to wallet2 observer
Bound 'on_payment_received' to wrapper
Added 'get_payments_count()' and 'get_transfers_count()
Switched back to raw copy for 'get_all_payments()', for pseudo-thread-safe iterations
Stupidness fixed.
Stupidness fixed.
Added cache to 'MoneroWallet' wrapper
Added block height in 'on_payment_received' for consistency
Added 'on_skipped_transaction' to observer
Added remaining methods to observer (not definitive)