Install Guide: $ROSE_HOME -> /path/to/rose

Subversion normally runs its hook scripts with an empty environment.
This change should avoid new admin users from being confused.
Merge pull request #874 from matthewrmshin/fix-doc-install-rose-home

Install Guide: $ROSE_HOME -> /path/to/rose
Merge branch 'master' into rose_arch
Merge remote-tracking branch 'origin/rose_arch' into rose_arch