added split function in time.timerange
fixed time.timerange.split to return timeranges and fixed its desc
fixed time.timerange desc
fixed spelling error
give time.timerange.split a default n value
Improved documentation for split method
Merge branch 'staging' of github.com:ToyDragon/sunpy into staging
Merge pull request #428 from ToyDragon/staging

Split in time.timerange