Enable option to add extra data when sending transactions

[elaineo]

Allow users to enter data when creating transaction

Currently hidden, just needs to be enabled. (Will be trickier for replay protection)

[tayvano]

http://classicetherwallet.com/?&data=4f524445525f31323334&gaslimit=21000&to=0x7cB57B5A97eAbe94205C07890BE4c1aD31E486A8&value=0.5#send-transaction

Data for Ethereum needs to be in HEX.

In addition, you cannot add additional data to send via replay protection contract as the data field is used to decide the actual address the ETC should be sent to.