Updated the sources to allow for custom curreny by the use of two new command-line flags.

New command-line flags:
--currency (-c): Allows the user to set an arbitrary currency symbol.
--suffixed     : Tells reckon to use the currency as a suffix, e.g. 10 SEK, as opposed to a prefix like $10.
Updated with suggestions from https://github.com/cantino/reckon/pull/11
Merge pull request #11 from zebh/currencies

Updated the sources to allow for custom curreny