WeekView

Can conveniently be created through XML, where a list of daynames should
also be supplied.
Still needs logic for displaying day number and month.
Refactored DayButton

Removed code only necessary for XML-creation of standalone DayButton. It
is not necessary when using creating WeekView with XML.
WeekView usable
Removes MainActivity in favor of TimeActivity
Merge pull request #5 from Timalex/development

Adds working WeekView