fixes #22, icons autohide with expected behavior

[cwjoshuak]

What's this PR do?

• Icons will autohide after 5 seconds on open if autohide is true

Notes:

1. Removed isExpanded check in if statement, it's always true on app open so the return is executed.
2. Added call to autoCollapseIfNeeded after setting up menu bar.

What are the relevant Git tickets?

#22

Steps to reproduce:

1. Open Hidden bar the first time
2. Choose option auto-hide after 5s
3. Quit Hidden Bar
4. Reopen
5. Auto-hide icon after 5s

Tested on macOS, 10.15.1

edit:
I don't do many PRs, will create new branches for separate fixes in the future.

[viettrungphan]

@cwjoshuak Thanks for your contribution, this bug we fixed with #30 feature.