Required columns on tables From 4.1.4.1 down to 4.1.5
Add missing table heading on Interaction components
fixes in response to @andyjohnson comments

fixes https://github.com/adlnet/xAPI-Spec/pull/424#discussion_r8100299 , https://github.com/adlnet/xAPI-Spec/pull/424#discussion_r8100339 , https://github.com/adlnet/xAPI-Spec/pull/424#discussion_r8100345
Addresses https://github.com/adlnet/xAPI-Spec/pull/424#discussion_r6925553
Merge pull request #424 from garemoko/morerequiredtables

Add optional/required for even more tables