Add ability to configure orchard components via config file

A special file "HostSingletons.config" is read at startup to
look for properties to set on host components.

--HG--
branch : dev

src/Orchard.Web/Config/Sample.HostComponents.config

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<HostComponents>
+  <Components>
+    <Component Type="Orchard.Environment.Extensions.Loaders.DynamicExtensionLoader">
+      <Properties>
+        <Property Name="Disabled" Value="true"/>
+      </Properties>
+    </Component>
+  </Components>
+</HostComponents>

src/Orchard.Web/Orchard.Web.csproj

@@ -122,6 +122,9 @@
       <DependentUpon>Global.asax</DependentUpon>
     </Compile>
     <Content Include="Config\log4net.config" />
+    <Content Include="Config\Sample.HostComponents.config">
+      <SubType>Designer</SubType>
+    </Content>
     <None Include="Media\web.config" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>