added a get_cpu_vendor to systemtools, so we are a littlebit more platform independent (should work on osx and bsd now) (closes #259)

revert part of previous commit that put all imports on the top, because it creates a cyclic dependency between build_log and config (config imports from build_log, build_log imports from config)

move all imports to the top, because it seems sometimes an import may fail if it's put 'inline' (see ageorges testing EasyBuild v0.5 on Ubuntu)

don't specify shell to use for modulecmd commands, it breaks stuff (" Usage is '/usr/bin/modulecmd shellname' ")

i.e. use /bin/bash as shell for root script (refs #180)

specify /bin/bash as executable for running system commands (required for Ubuntu), check if environment-modules is installed (refs #180)

specify "/bin/bash" as executable for running system commands, make sure that environment-modules dependency is installed