Proposal fix for: Don't throw an exception when you can't connect to server Ref:#57

see: https://github.com/joomla-extensions/patchtester/issues/57

@wilsonge @mbabker can you have a look into it?

I'm not 100% sure if we can simple add here https://github.com/zero-24/patchtester/blob/patch-1/administrator/components/com_patchtester/PatchTester/Helper.php#L29 one param and / or how this function is called.

### What this should do

- User enter the PW/Username
- We try to connect github and fail
- We create a github objekt without PW / Username (maybe we need to add the token here too?)
- We try to connect github
- If it fail we have throw a RuntimeException
- if it is the first connect to github fails we send the message 'Please enter User namen' and 'can't connect to github' as messages.