Merge pull request #431 from apoloval/port/430

[PORT] Do not force zero in X axis of order book chart
Add new `ObservableBeanProperty` class

This class makes possible to observe the property of a bean that, in turn, is
part of another property. The first baby step to have a flatmap function for
properties.
Move & rename `ScalaFxImplicits` as `coinffeine.gui.beans.Implicits`
Extract pimp classes from `coinffeine.gui.beans.Implicits`

That's too much code to be inlined in `Implicits`.
Add unit tests for `ObservableValuePimp` class
Add a flatMap operation to `ObservableValuePimp`
Fix cancel order button not disabled when pressed

The order cancel button was not disabled when it was pressed and the selected
operation was cancelled.
Merge pull request #433 from apoloval/port/432

[PORT] Fix cancel order button not disabled when pressed #432