Added refresh for home screen.

[tonyday567]

Adds an ability to refresh the list contents of the spacemacs home screen. I'm not sure what the general key mnemonics for refresh are, and chose "a" as the key as the first one I could find.

Type "a" in the *spacemacs* buffer to test.

This is related to #3720, but can be PR'ed independently.

[travisbhartwell]

I don't have an opinion on the keybinding, but this is a functionality I've wanted for a while, so 👍

[StreakyCobra]

The shortcut may conflict with #2677 if merged.

[nixmaniack]

We're tending towards having gr as refresh in most evilified states(magit, neotree comes to my mind)

And yes 👍 for this!

[TheBB]

Yep, I think you can bind both gr and C-S-g in motion state, and g in the default map (for Emacs editing style users).

[robbyoconnor]

I love this ❤️ 🎉

[justbur]

conflicts with #3426

[justbur]

Sorry I should have been more specific. I just meant that if #3426 is merged this will have to change and vice versa

[syl20bnr]

#3426 has been merged, @tonyday567 can you rebase your PR ?
Thank you !

[tonyday567]

There you go :)

[syl20bnr]

Thank you for the PR and sorry that we did not merge it. Refresh of the home buffer is now on C-r. Also your repository is gone so I cannot fetch this PR.
Thank you again 💜