Manage visibility of account data from external networks. Improve accounts list (I2-2)

Showing "total sales" and "total purchases" in accounts list.

Correct format in several amounts.

First version on account list to views.
Needs work:
- Repeated account if it has several users.
- Total sales and total purchases columns.

No repeated rows when account is managed by several users.
Needs work:
- Total sales and total purchases columns.
- Expose filters: account name and user name.

Total sales column.
Needs work:
- Expose filters: account name and user name.

Patch #7: list with account, user (username, firstname, surname), email and balance. With filter exposed searching for account, user or email. The filter, pager and table sorting works with ajax.
Not possible to list "total sales" and "total purchases" since when the transactions history is long, the query takes too much time. Instead of listing this info, the user can click on "user" column and see this info in a new page.

It needs some changes:
- View must be a block, not a page, to avoid access in the view's path.
- It must list only active accounts, not locked, hidden, closed nor interexchange ones.