Price float bug

[StefanBoodt]

Please, fill all relevant items:

• [ ] I have read CONTRIBUTING.md
• [x] I have tried with the latest pre-release version and I still can reproduce the issue.

  Tribler version/branch+revision:

Triller feature/market

Operating system and version:

Ubuntu 14.04

Expected behavior:

The float method in price returns a float.

Actual behavior:

The float method in price returns a Decimal.

Steps to reproduce the behavior:

Call float(price) somewhere. Additionally isinstance can be called.

Relevant log file output:

TypeError: float returned non-float (type Decimal)

[mitchellolsthoorn]

Fixed the problem,if it works close the issue please

[StefanBoodt]

I saw. It seems to work now.