Multiple updates to clarify included Perl modules, authorships and copyrights.

1. Added mentions of Perl module authorships and copyrights to DESCRIPTION file.
2. Removed File::Basename and Getopt::Long, since these are Core Perl modules and should be available.
3. Clarified references to included Perl modules in function help files and the INSTALL file.
4. Added the INSTALL file to the root package folder for each of location in the package tarball on CRAN. Still present in 'inst' folder so that it is present post package install.