AmountOfMoney add support for `bits`

[rgstephens]

Add support for amounts in bits for English. Two, four & six bits (.25, .50 & .75)

[chessai]

I hadn't heard of this before. Here is some context for other readers of this issue: https://en.m.wikipedia.org/wiki/Bit_(money)

[rgstephens]

Thanks for adding the reference. The Robert Louis Stevenson shopkeeper example is where I first heard this as a kid and I also hear it used when referring to bet amounts.