#68 - adds gradient and rounded options

[wrabit]

• adds option for gradient:

:gradient="[
    { offset: 0, color: '#25ba00'}, 
    { offset: 50, color: '#ffc000'}, 
    { offset: 100, color: '#FF0000'}
]"

• adds option for rounded:

:rounded="true"

For some reason with the simple horizontal line the ends are clipped so you can't see the rounded end caps.

See updated demo.