preserve curent working directory for parrot packaging tool
add -w parameter to set the pwd for parrot_package_run
add /bin/sh into namelist
allow chroot_package_run support 3 operation models:
1. only run one command; 2. entre into one shell using --shell /bin/bash; 3. entre into /bin/sh by default.
allow parrot_package_run support 3 operation models:
1. only run one command; 2. entre into one shell using --shell /bin/bash; 3. entre into /bin/sh by default.
modify the help doc of parrot_package_run and chroot_package_run
add complete_path to transfer relative path into absolute path
change possbile bashism to obtain the first character of a string
change the location of the code mounting virtual fs
remove --shell parameter
modify doc for packaging utility
Merge pull request #499 from hmeng-19/parrot_pwd

Parrot Packaging: Save Working Directory