Allow different number of decimal places

Release has been updated to allow non-two-decimal-place amounts to be sent to PaymentExpress.

Only allow two decimal places

Payment Express' api does not like more than two decimal places

Minor: include more information when throwing exceptions

v1.0.2

Add additional information into exceptions

Fix phpdoc

Minor - fix phpdoc to allow your IDE to correctly resolve PxPayment variables

First release

Update documentation

Tidy formatting