bugfix for Carthage

• fixed bug that @IBDesignable, @IBInspectable cannot be seen in Interface Builder when installed with Carthage.

update RangeSeekSliderDelegate

• add default implementation rangeSeekSlider(_:didChange:maxValue:) in RangeSeekSliderDelegate

Update README

• update README
• add Gitter link.

Update LICENSE

1.0.1

update LICENSE

Initial Release

1.0.0

update README.md