Move health checks to a separate function in bats test file

[MurzNN]

Now, regarding to the template file, we have to write checks twice:

• In @test "install from directory"
• And in @test "install from release" - the same lines.

Will be good to move that to a separate function, to not have two places to manage them.

So, I've created a function health_checks() that contains only a single instance of checks.

And have moved it to the top, because it will be edited more frequiently, than test functions.

[MurzNN]

Seems bats doesn't support functions with all commented lines, so I've just added one real line there and it starts working: