[#54] removed setCurrencyChangeCallback API call

not used at the moment and we don't even know how
it's going to look
[#54] return real profile data in getClientInfo()
comment fix
[#54] updated getTransaction API call

- send timestamp in proper ISO format
- send amount as an absolute value
- removed broken 'confirmations' field
- renamed: txid -> id
- renamed: time -> timestamp (I'll try to add a time field with a Date
  object later)
- added 'received' boolean field
- replaced 'address' and 'category' with 'inputAddresses' and
  'outputAddresses' lists