Added check for the cvmfs lock file before initializing,
so that parrot can emit a useful message rather than hanging
in cvmfs_init when someone else is sharing the cache directory.
Fixes #102
Update work_queue_worker path in test_runner.common.sh
Fix cp path for visualizer
Minor visualizer fixes.

- Replace underscores with spaces for axis legends.
- Use absolute paths when copying webpage support files.
Merge branch 'master' of github.com:cooperative-computing-lab/cctools