fix CmAccount instancing in BuyBookingToken function

[VjeraTurk]

Why this should be merged & How this works

• Fixes using the bot address ( transportOpts.From) instead of cmAccount address.
• Skips the checkAndApproveAllowance before minting (the approving the allowance is done during the buy operation that is triggered by the cmAccount.buyBookingToken() function call).
• Uses CAM instead of EURSH in mintnbuy.go example
• Add example for Test Token in mintnbuy.go example (with comments)

How this was tested

Buy running mintnbuy.go and via postman using Test Token, CAM and EUR.

[VjeraTurk]

DONE: Test with test token @nkoljanin