Update README.md

Fix directory reference.
Update installation.md

Add info to use configuration file from non standard location.
Merge remote-tracking branch 'upstream/master'

Merging the latest changes from Victor.
Merge branch 'master' of https://github.com/fuhlig1/libvirt-shell-functions
Fix error with path substitution in bash.
Merge pull request #2 from fuhlig1/master

Fix error with string manipulation in bash