Added a CommandWithTerm Class

Added new CommandWithTerm Class similar to the CommandWithMeta Class.
Designed to reusable for different object types. Currently this is draft and I am still testing it. Just wonder if I was on the right track with this solution. Feedback is requested. I will write tests when I know that I am on the right track. 

Related #1379
I believe it should mirror wp post meta list. Requiring taxonomies make this function less useful. If you don't know the name of the taxonomies you will not be able list it. For example tags and posts formats are named post_tag and post_format. Unless you know those names, you would not  be able to list them. If you do a list of all terms, you can them work out the taxonomy list.