fix age to be calculated with more than just year.

[ravishende]

In /signup route in views.py (used almost everywhere that requires age) and in the get_age() function in app.py (used in profile.html), age is calculated as datetime.year-birthday.year. This only takes into account the years and not the days/months, so that means if someone hasn't had their birthday that year, it will still say their age like they have. In essence, everyone has a birthday of January first when calculating age with this model. To fix this, subtract datetime-birthday and then take only the years portion of the difference or something along those lines.

[ravishende]

I made a function called calc_age() that does work as a stand alone function, but when I implemented it into the code base, mainly in /signup in views.py, a new error pops up where it no longer writes to vars.txt the variable 'half_user', so when it goes to read it, it doesn't see the 'half_user' there, so it throws an error once signup is completed. To find it easier, it's around lines 132,135, and 154 in views.py