Installer fixes.

- Set correct update server URL.
- Add missing '$' resulting in a bad existence checker path in
  the WebM postinstall script.
- Remove keystone registration and unregistration of XiphQT.
- Remove XiphQT postinstall/postupgrade script, and remove
  the reference to it from the XiphQT installer.

Change-Id: I6fb3737809beddb2e898555d0fa7094e8388179f
4 files changed