Implement the main form of operations view

This is a initial implementation of the form corresponding to the operations view. It provides the controls necessary to insert the properties of a exchange and submit it to the broker set.

![captura de pantalla 2014-07-02 a la s 13 48 50](https://cloud.githubusercontent.com/assets/738507/3455630/d4ec7868-01e4-11e4-8736-c1838ffe932e.png)

The text box is not constraining the number of decimal digits introduced by the user. Actually it is possible to introduce text, unless the _Submit_ button will be disabled in such a case. 

Let me check how to constraint the input to a valid digital number and so.