updated rcas.Rmd
updated rcas.Rmd

- rcas.Rmd script can be run from different directories now. No need to hard-link the scripts to the working directory.
- Each chunk in rcas.Rmd is given a name to make it easier to trace the progress of a run.

BIMSBbioinfo/RCAS-tools,dyusuf/RCAS,dyusuf/RCAS,BIMSBbioinfo/RCAS-tools,BIMSBbioinfo/RCAS-tools,dyusuf/RCAS