Margin Updates in the Aave FCM.

[reyalabs]

Make a decision on the introduction of an updateMarginInATokens function in the AaveFCM

[CyclopsRex]

I don't know much about this issue but if we are writing new solidity code we should do it sooner rather than later.

[reyalabs]

We need to add an option for a trader to update their margin in terms of aTokens, this function should only support a top-up (e.g. a position margin delta). Rationale behind this function is to let traders perform out-of-money unwinds.