Adding a bootstrap command that simplifies jenv setup

[nwillc]

I'd like to be able to bootstrap a jenv setup for a user so they don't need to change their init scripts or manually add jdks. In particular this is being done to allow CI scripts to automate the jenv setup and then use jenv.

[nwillc]

Any thoughts on this contribution?

[gcuisinier]

Hi,

I need time to check and integrate.
But sounds interesting 👍

[ssbarnea]

👍

[jesperronn]

👍 from me too. This looks very appealing and could simplify my setup so that I can integrate jenv more tightly in my .dotfiles (to bootstrap my new machine properly).

@gcuisinier since February, did you have time to consider and possibly merge?

[b-long]

Adding a 👍 . @gcuisinier , any thoughts on bringing more folks on as authorized collaborators to this repository?

[ghost]

This PR needs some work. It only supports bash and fails if there are no JVMs installed at all. But it is a good idea and I might do something like this.