Change the upgrade command to print migrate blueprint instructions

[mraible]

Overview of the feature request

We're getting a lot of issue reports about the jhipster upgrade command not working. Rather than having to keep telling to try the migrate blueprint, let's just print the instructions to the console.

Motivation for or Use Case

Reduce support required.

[mshima]

The idea is to update the upgrade with a reduced version of the migrate blueprint. And add a info about the advanced features of the migrate.
I plan to do it this week.