Remove unnecessary InstalledByMsi flag

src/Samples/CSharp/MakeConst/Impl/source.extension.vsixmanifest

@@ -28,7 +28,7 @@ governing permissions and limitations under the License.
     <DisplayName>Make Const for C#</DisplayName>
     <Description>This is a sample code issue extension for the Microsoft Roslyn CTP.</Description>
   </Metadata>
-  <Installation InstalledByMsi="false">
+  <Installation>
     <InstallationTarget Id="Microsoft.VisualStudio.Pro" Version="14.0" />
   </Installation>
   <Dependencies>
@@ -37,4 +37,4 @@ governing permissions and limitations under the License.
   <Assets>
     <Asset Type="Microsoft.VisualStudio.MefComponent" Path="MakeConstCS.dll" />
   </Assets>
-</PackageManifest>
+</PackageManifest>
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