Allow invocations from other locations than the project dir

[DiCanio]

To use the project in its current state one needs to cd into the project directory and call the scripts.
This is kinda tedious and we should allow developers to use the scripts through symlinks and the like.

However, this is currently not possible due to the use of pwd. So, from wherever a developer will invoke any script, his current directory will be marked as the current working directory. Since there is a script that clones repositories into the current directory, this can have effects which may be undesired or even devastating.

Proposal:
Replace any usage of pwd with a routine that identifies where invoked scripts are actually located (withinin the project directory). Make use of this information throughout affected scripts to avoid any changes outside of the project directory itself.