time_date tests, month() +1

- I created tests for input/time_date.js. Thanks to @antiboredom for help testing millis() with a p5mock!

- I found that month() returns 0 for January, so I added a +1.

- Does anyone have advice for how to require/load outside files for grunt mocha tests? I started to make tests for input/files.js like loadStrings() and loadJSON(), but haven't figured this out.