Added China Inter Bank Holiday calendar

China Inter Bank holidy schedule is different from SSE (Shanghai
Securities Exchange). Some weekends are good working days for inter bank
market. Now the working weekends are hard coded for the years 2013 and
2014
Replace hard tabs with spaces.
Include required header only.
Rename inner class for consistency.
Hide implementation of working weekends as set.
Export new interbank Chinese calendar.
Merge pull request #93.