Added Taiwan calendar, created EphemMixin

EphemMixin refactors a bit of JapanCalendar, and adds a method
to compute the Solar Terms (used for Taiwan Qingming festival)
Updated README.rst to include Taiwan
Cleaned up files

- New lines at the end of some files
- Removed temporary comments
Removed unused method in JapanCalendar class (calculate_equinoxes)
`days` is now inherited and appended.
Adapted tests to be compatible with Python 3

In Python3 you cannot use 04 or 05 as an integer, which is what
was used in test_core.py
Merge pull request #53 from pierrrrrrre/master

Taiwan Calendar