Make manager view optional

[k-thorat]

Thank you for all your work for awesome logging tool!

In this PR, I have added option to use Dotzu without Bubble Head.

We are using Dotzu with some in-house debugging tools. We were looking to manage all the debugging tools at one place.

Summary:

• Made Manager window & controller optional
• Created Dotzu config to extend setup options in the future.
• Opened access to ManagerViewController from DotzuManager
• Updated example with config
• Updated ReadMe to show usage of config

Thanks!

[CocoaDebug]

Hi, I released DebugMan, it is forked from Dotzu. Welcome to use! 😃 thanks! @k-thorat