Changes strokeWidth to always equal strokeWidth. (#80)

Adds opacity set to 0 on 0 progress (ptg), otherwise 1.

Due to the CSS transition and element width race-condition there is a need to keep the width greater than 0.

Co-authored-by: mjfwebb <michael@w3bb.net>

Author: mjfwebb

src/Circle.js

@@ -107,7 +107,8 @@ class Circle extends Component {
           d={pathString}
           stroke={stroke}
           strokeLinecap={strokeLinecap}
-          strokeWidth={ptg === 0 ? 0 : strokeWidth}
+          strokeWidth={strokeWidth}
+          opacity={ptg === 0 ? 0 : 1}
           fillOpacity="0"
           style={pathStyle}
           ref={path => {