Added contains functionality to timerange.
Update README.md
Added contains functionality to timerange.
Merge branch 'timerange' of https://github.com/mateoi/sunpy into timerange

Conflicts:
	CHANGELOG.md
Added changelog entry
Fixed __contains__ docstring and made PEP8 fixes (both in timerange.py)
Merge branch 'timerange' of github.com:mateoi/sunpy into mateio-master

Conflicts:
	CHANGELOG.md