UiPoolDataProvider should provide aTokenSymbol with aTokenAddress

[Jdecristi]

trafficstars

Bug Report

Aave-Interface issue #942

Description

When adding an aToken in the UI the aToken symbol is wrong for some networks. This could be fixed by providing the aToken symbol along with the aToken address.

Steps to reproduce

1. Go to the reserve-overview page for a token on a different network than Ethereum Example Site
2. Click on AddTokenDropdown,
3. View incorrect aToken Symbol

Expected behavior

The dropdown should display the proper aToken Symbol

Additional Context

Before		After