bug 23810 - begin preparing existing code for pbcore namespace harmonization

[git-p4: depot-paths = "//depot/software/bioinformatics/tools/pbbarcode/": change = 126438]
Fixed functional specification for 2.1 software - described the file format and execution parameters. Also added a README.rst at the top-level.

bug 21908

[git-p4: depot-paths = "//depot/software/bioinformatics/tools/pbbarcode/": change = 126559]