Prevent selectors from exceeding CalendarStrip's height.

Left/right selector responsive sizing limits to container height.
Fix WeekSelector shouldComponentUpdate criteria for size prop updates.

Add responsiveSizingOffset, fix circular reference error

Fix circular reference error when passing component as left/right selectors.
Add prop responsiveSizingOffset to tweak computed day component size.

Responsively size calendar strip

CalendarStrip's height is dynamically computed based on its container's width.

Refer to the Readme for new props innerStyle, maxDayComponentSize, and maxDayComponentSize.

See #14

Switch to `prop-types` package due to deprecation of React.PropTypes.

See https://facebook.github.io/react/blog/2017/04/07/react-v15.5.0.html

Performance, features and bug fixes

Improve performance (#33).
Per-date custom styling (#32).
Fix examples (#31).
Use transparent background for days that aren't selected (#42).
Bug fixes.

Features, API changes

Use LayoutAnimation to improve performance (#25).
Numerous bug fixes and enhancements.

Breaking changes:
The props selection, selectionAnimation, borderHighlightColor, highlightColor have been consolidated into daySelectionAnimation. This makes it consistent with calendarAnimation prop.