Remove unused function for DIC calculations
Make compatible with Octave and additional unix systems

- The 'unix' and 'dos' functions are not interchangeable in Octave
- Also look for jags in /usr/bin/ (Ubuntu)
Convert to absolute file paths and localize cd()'s
Add option to pass model as string
Use OS-specific temporary directory as default working directory. Clean up after use.
Merge pull request #1 from cdcarroll/master

Fix compatibility issues for Octave and Ubuntu