default hamster build to /usr/local results in broken setup

Created by: FelixSchwarz

This is basically about #221 (closed) (opening a new ticket because I don't have any special access privilege for this project). I looked into this and this is for sure a real issue: Basically the default hamster install process is broken. A quick fix could be #276 but I'd like to fix the issue completely. The pull request just shifts the problem to the user.

From my POV all executables must ensure that the "hamster" module can be loaded via sys.path so I guess the executable must manipulate sys.path if necessary. Probably the "waf build" step is the right place to do this. Alternatively we could modify the default path for waf to /usr.