[HttpFoundation] Added missing phpdocs and fixed codestyle

Added phpdocs for properties and methods that didn't have any or felt short in my opinion, along with some cs fixes like the aligning of assignments etc. 

The idea behind these fixes is that it may increase code readability and can help developers extending these classes to assess the function of each segment of code quicker. It also could help create a more consistent codestyle across the components (primarily using php-cs-fixer).

If appreciated I'd be happy to do the same to the other components, just give me a shout.