Make psh multi user ready

[pascal-zarrad]

Is your feature request related to a problem? Please describe.
At this time, psh can only be installed for the user that runs the script. It should be possible to mentoin another user as a parameter.

Describe the solution you'd like
Implement a parameter like --user that allows to install psh onto another user account than the current one.

[pascal-zarrad]

While making psh multi-user ready, the logging functions have been outsourced into a seperate lib script

[pascal-zarrad]

Merged