minor
introduce MetroButtonCommandPasswordBox
introduce ButtonFontFamily attached property
use ButtonFontFamily attached property (TextBox)
renaming...

MetroButtonCommandPasswordBox ->MetroButtonPasswordBox
fix using new style key MetroButtonPasswordBox
renaming

ButtonCommandMetroTextBox -> MetroButtonTextBox
Merge pull request #1097 from MahApps/993-punker76-ButtonCommandMetroPasswordBox

introduce ButtonCommandMetroPasswordBox