BTER error handling for small amounts

[Desrever Nu]

The BTER wrapper is currently not handling at least one error correctly.

Try to enter an order with a very small amount

 testSell(0.001, 0.004, Constant.NBT_BTC);

The wrapper will throw an exception ( msg => Your order size is too small. The minimum is 0.0001 =

[Desrever Nu]

handle result=false along with (fix #151) to result="false"

[Nicolò Paternoster]

handle result=false along with (fix #151) to result="false"

→ <<cset c23757cc1d44>>