AUI Progress Bar should use percentage instead of px when horizontal to make it responsive

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.0.x, master, master-deprecated
• Fix Version/s: 2.0.x, master, master-deprecated, 3.0.x, 2.0.0.75-deprecated
• Component/s: Progress Bar
• Labels: None
• Git Pull Request: https://github.com/mairatma/alloy-ui/pull/307

Currently the progress bar width can be set to a percentage but the width of the progress indicator is set in px and is calculated based on the current width of the progress bar. This causes an issue when a window is resized because the progress bar's width changes with the window but the progress indicator does not causing an inaccurate representation of the actual progress percentage.