Add types and reduce function context

[belcherj]

Fix

We pass an object to a isDevConfig but it only uses the one property. This changes the function to only accept that property and types it as a boolean. I updated the one place where the function is called. I also updated the tests.

Test

1. Run Simplenote with console open.
2. In dev you should see: Simperium config: Development
3. In prod you should see: Simperium config: Production

[belcherj]

Do we need this code? Is this helpful information? Could we combine it with the dev badge that gets added to the bottom of the note editor?

[dmsnell]

Do we need this code?

For this PR I think your refactoring and reduction in scope is a positive step. Maybe we can come back later if this is problematic and assess if it's needed somewhere we're not immediately aware of?

[belcherj]

Agreed, I want to come back and delete the function all together.