Update MetroProgressBar.cs

Fix of the control when you set isindeterminate = false and in runtime change to true, the size of the storyboard not have the new size
Update readme.md
Update MetroProgressBar.cs

add tabs
Merge pull request #817 from spiritdead/patch-4

Update MetroProgressBar.cs
Dispatcher.CheckAccess not applied everywhere
Changed ()=> to new Action(()=>
Merge pull request #819 from xxMUROxx/hotfix/MetroMessage-Threading

Dispatcher.CheckAccess not applied everywhere