Added Spark Wiring Calendar (Date & Time) Library using on-chip RTC
Implemented Spark Wiring Time Lib (earlier Calendar - Testing ongoing)
Completed and Tested onchip RTC based Time Library
Reimplemented spark_wiring_time using GNU C library (time.h)
Added time zone adjustment and updated arduino's month and weekday calls
Simple time skewing to correct small clock drift #148
Merge pull request #148 from spark/feature/calendar

Feature/calendar (read as feature/time)
Merge branch 'master' into bug-fixes
Spark_Save_Firmware_Chunk() now returns next_chunk_index instead of bool