Fix debathena-chromium-config per review notes:
* Use substvar to specifically depend upon the correct chromium package
* Avoid pulling in space shooter by explicitly specifying chromiun (>= 1)
* Fail if configuration file transform does not work



git-svn-id: svn+ssh://svn.mit.edu/athena/trunk@25998 728af825-273c-0410-89f9-f7d3b574a069