Preparing a cluster installation fails at Setup Support Rules Step (Not Clustered or the cluster service is up and online)
So, finally after more investigation I found the right post explaining my problem and the solution.

It turns out the article was the one that dco pointed out. The thing is this: the problem I was experiencing was not solved with the slipstreaming technique (the install with SP2) but with other thing mentioned there further down the road (Issue 2: The "Cluster Service verification" rule fails when you try to install a SQL Server 2008 R2 failover cluster instance).

Turns out I had to enable the "Failover Cluster Automation Server" Feature in my Windows 2012 R2 boxes.

Thanks everybody for your help on this matter, especially dco for pointing me to that website. Since the resolution that dco offered (slipstreaming with SP 3) was not the solution to my problem I did not accepted that one as the answer (so that future searches with other people looking to fix this same problem don't end up on a wild goose chase).