Added Accessors and Mutators

These methods return the protected variables we need to display the
posts in the newsfeed. The mutators will eventually alllow us to edit
posts, but are not fully implemented. We still need to implement the
queries that will connect to the DB and modify the posts's information
based on which mutator gets chosen. We may just choose to make one
master mutator that changes all fields/variables at once, but there are
some possible concerns with that.