Wallet: move processPendingTx & processConfirmedTx to prototype

also, move processTx out of Wallet scope
Wallet: move getPrivateKeyForAddress to prototype

also, move the assert to the end to simplify the logic
Wallet: remove unncessary comments
Merge pull request #2 from weilu/dcousens-wallclean

Clean up Wallet constructor function
Merge pull request #258 from dcousens/wallclean

Wallet clean
Wallet: use indexOf explicitly over include*
Wallet: use === when comparing with undefined
Wallet: use __processTx over a free function

The use of bind in this case wasn't idiomatic.
Wallet: assign indexOf in the same step
Transaction: deprecate Tx signing methods
TxBuilder: Initial commit and tests
TxBuilder: use data fixtures for invalid tests
TxBuilder: transform all signatures once
TxBuilder: use build/buildIncomplete over boolean
Wallet: use TxBuilder instead
TxBuilder: fix missing code path
TxBuilder: add pubKey test fixture
TxBuilder: add invalid nulldata case
TxBuilder: sign after error checking
TxBuilder: remove unnecessary assert