Add Calendar Function

[bbland1]

Changes

Created a calendar.html, calendar.css and calendar.js
(separated out the css because didn't want to interfere with the base css as I worked through it all)

I looked at the sigma and added spaces for each thing on the dash board but the calendar is the only part with function so far. This creates the calendar of the current month and marks the current date. It also allows the user to use the arrows next to the month/year info to go forward and backwards to a new month. It populates the month with what should be the correct first day of the month and the total days.

There are some classes in the css that would be used to display the predicted period if that is a feature, a logged period and the flow of the logged period if add. The js for that isn't made yet because I just thought about that but wanted to push a smaller pull request instead of giant change files.

Fixes #53

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings