replaced ``/home/qiime`` with ``$HOME``
all instances of ``/home/ubuntu/qiime_software`` are now ``$QIIME_DIR``
remaining instances of ``/home/qiime`` and ``/home/ubuntu`` are now
``$HOME``
the files in which ``$QIIME_DIR`` was added also have explicit exports
in place to define that environment variable
changed  to /Users/mcdonald
Merge pull request #935 from wasade/issue313

Issue313