Allow passing dynamic cache configuration to the decorators

[suzdalnitski]

This PR enables dynamic cache configuration with decorators:

defmodule MyApp.AccountService do
  @decorate cacheable(cache: {MyApp.AccountService, :get_cache, []}, key: id)
  def get_account(id), do: ...

  @decorate cache_put(cache: {MyApp.AccountService, :get_cache, []}, key: account.id)
  def update_account(account), do: ...

  def get_cache, do: Application.fetch_env!(:my_app, :cache)
end

[coveralls]

Coverage remained the same at 100.0% when pulling 1c0cca2 on hiivemarkets:dynamic-cache-decorator into 530fa4d on cabol:master.

[cabol]

@suzdalnitski the dialyzer is failing, I think I know why, but that will require some changes, so, since the PR looks overall good to me, I will merge it for now, and will push some improvements and the dialyzer fix later (very soon).