Figure out how to access/edit entries in the db using function calls

[lhmcgann]

THIS IR RLY IMPORTANT TO FIGURE OUT: OTHER ISSUES (ADD ENTRY, DELETE ENTRY) RELY ON KNOWING HOW TO DO THIS

figure out how to structure the backend and model_mongodb code to use the Diary class and Model methods to accomplish goals

Be able to update existing entries entries are embedded documents, so do we need to modify the save() function to call update() with more than just self (i.e. update operators)? Have multiple save/update functions? time estimate: 6hrs

[lhmcgann]

5/19: spent a little less than 1hr getting /diaries/ route to hopefully return the correct diary JSON object. See commit

[lhmcgann]

5/24: spent maybe another hr writing the remove() function of the non-embedded Entry class. See commit

[lhmcgann]

I spent a lot of time getting this to work. After understanding the basic principle (above hrs of work), was able to write all the prelim functions for Entry relatively quickly (1hr above, maybe another hr). Spent at least 4hrs testing though --> 7hrs total. And that might include work on the diaries too.