Added more specific exceptions to increase control outside module.
Added Travis config.
Merge pull request #31 from codemonkey2841/master

Added more specific exceptions to increase control outside module.
Remove Python 3.3 from test platforms.
Fixed tests for minimum order sizes.
Sort trade history items (because they are received in a dict and are therefore not necessarily sorted).
Handle float inputs to truncateAmountDigits (necessary on Python 2.6).
Ensure that invalid pair strings with more than one underscore are only split once.
Updated tests to check for new exceptions.
Pass decimal.Decimal values to functions under test (necessary for tests to pass on Python 2.6).
Pass strings instead of floats to decimal.Decimal (necessary for Python 2.6).
Added Travis-CI button to README.
Added eur_rur pair.