Add Title component for Accordion.

Signed-off-by: Lee <jessy1092@gmail.com>
update checkbox: support disabled, readOnly, init function.
- Add getReadOnly function in stateSelector.js

Signed-off-by: Lee <jessy1092@gmail.com>
update dimmer: support disabled, active, init function.

Signed-off-by: Lee <jessy1092@gmail.com>
v0.1.2
- Add `<Title>` component for Accordion.
- update Checkbox: support `disabled`, `readOnly`, `init` property.
- update Dimmer: support `disabled`, `active`, `init` property.

Signed-off-by: Lee <jessy1092@gmail.com>
Dropdown component support `active`, `disabled` properties.

Signed-off-by: Lee <jessy1092@gmail.com>
Update dropdown docs.

Signed-off-by: Lee <jessy1092@gmail.com>