Improve code quality with regard to the code review

[dilanSachi]

Purpose

$subject

ToDo

• Add frontend http service api docs
• Improve https://github.com/dilanSachi/gcp-microservices-demo/blob/08789d2abfc8781be5fdcb1680255e1484e7f7db/currency/currency_service.bal#L64 since it can cause an overflow
• Find a way to merge money_utils.bal in frontend and currency

[dilanSachi]

Improve https://github.com/dilanSachi/gcp-microservices-demo/blob/08789d2abfc8781be5fdcb1680255e1484e7f7db/currency/currency_service.bal#L64 since it can cause an overflow

int units = <int>targetAmount.floor();
Since targetAmount is coming from units and units is denoted as int64 in the proto definition, we can make sure an overflow won't happen

[dilanSachi]

@chamil321 Updated http method docs
777fa7a

[dilanSachi]

Find a way to merge money_utils.bal in frontend and currency

In the original sample, money utils are duplicated in both checkout service and frontend. So I think its ok if we have the same approach.

[gimantha]

LGTM