Enable light deployment of the protocol

[eboadom]

Closes #12

[eboadom]

What was done in the smart contracts on 80fd095:

• On LendingPool, just changed the immutables to storage variables appended at the end of LendingPoolStorage.
• On AToken, VariableDebtToken and StableDebtToken, changed the immutables to storage variables appended at the end of each of the contracts' layouts. In the case of the _incentivesController immutable on IncentivizedERC20, it needed to be moved to the children aToken/debtTokens, to not break compatibility with previous storage layouts. This obliged to change the IncentivedERC20 to abstract, with some abstract functions. Also on aToken/debtTokens, the explicit constructors are not needed anymore, and the initialize() functions receive extra parameters.
• LendingPoolConfigurator has been adapted to support the previous changes and now it only allows to initialized reserves in batch.
• Additional helpers, not part of the protocol and used mainly for simpler deployment procedure have been modified accordingly to the changes mainly on LendingPoolConfigurator

P.D. Tests and deployments have not been adapted yet

[The-3D]

This merge request contains a refactoring to enable lighter deployments of different markets and configuration for various sidechains/L2s. It has been extensively reviewed