Fixes #250 - Add boolean option for passphrase

[isaacvr]

Fixes #250

Changes:

• Add with_passphrase option to fsm_getKeyPairAtIndex. This allows you to enable or not the use of a passphrase for mnemonic and, therefore, to use two generations of different addresses, as long as the device has the passphrase option enabled.
• In other uses of this function (fsm_getKeyPairAtIndex) outside the signing process, the argument with_passphrase is passed as true, because before this change that was the behavior. Note that in the future the selection of passphrase or not, should be considered in the future in these cases.

Does this change need to mentioned in CHANGELOG.md?
yes

Requires testing
yes

Comments about testing , should you have some