Added get_executable_path() function.

Necessary to find correct executable paths for python and R targets and not have duplicate code.
Added r-package deploy code to Application class.
Removed custom R deploy code.
Renamed package-name and package-repo.

Now r-package-name and r-package-repo to be clearer.
Added app_sect argument to get_executable_path().
Fixed string formatting issue.
Fixed issue with using app var instead of self.
r-package deploys can now be performed in parallel
Merge pull request #23 from jrrideout/issue_3

Added new r-package build-type.