Update to Documentation

I'm going through configuring and installing visionworkbench right now. I noticed the docs weren't up to date. 

The INSTALLGUIDE currently says the configure flag to specify additional search paths for packages is --with-paths... However running ./configure --help says that the flag has been changed --with-pkg-paths. I just updated the INSTALLGUIDE to reflect the changes. If I come across any more out of date docs I'll try to patch them up. (updating docs is a pain)