Add Converters namespace to exported namespace (#1202)

There are a lot of useful converters in the Converters namespace, and none of them are exported. This change allows access to that location through the xmlns.

Author: tadgerb

MaterialDesignThemes.Wpf/Properties/AssemblyInfo.cs

@@ -17,6 +17,7 @@
 [assembly: XmlnsPrefix("http://materialdesigninxaml.net/winfx/xaml/themes", "materialDesign")]
 [assembly: XmlnsDefinition("http://materialdesigninxaml.net/winfx/xaml/themes", "MaterialDesignThemes.Wpf")]
 [assembly: XmlnsDefinition("http://materialdesigninxaml.net/winfx/xaml/themes", "MaterialDesignThemes.Wpf.Transitions")]
+[assembly: XmlnsDefinition("http://materialdesigninxaml.net/winfx/xaml/themes", "MaterialDesignThemes.Wpf.Converters")]
 
 // Setting ComVisible to false makes the types in this assembly not visible 
 // to COM components.  If you need to access a type in this assembly from