Minor UI improvements to WiX BA.

Show the package currently being installed and trim off irrelevant noise
from the beginning of the progress messages.
Merge pull request #20 from robmen/wixba-uiimprovements

Minor UI improvements to WiX BA.
Co-locate Votive file association custom actions.

The custom actions to set the latest Visual Studio version were in the
Votive product file but are only used by the file association code. This
commit brings them together in the file association code.
Allow share delete on get/set file timestamps.
Add TouchFile custom action.

New support for updating the modified date/time of a file.
Replace devenv /setup call with fast extension update mechanism.

The devenv /setup call when installing the WiX toolset can take minutes
to complete. Fortunately the VSIX installation method introduced
another way to complete the registration of extensions. All that is
necessary is to touch the "extensions.configurationchanged" file.