baseimage: use `sed -i -e ...` instead of `perl -pi -e ...` to edit config files

perl package is still installed (because git package depends on perl)
debian: updated README.md
baseimage: updated README.md
Merge pull request #6 from minimum2scp/feature/use-sed

baseimage: use `sed -i -e ...` instead of `perl -pi -e ...` to edit config files
baseimage: updated README.md
debian: updated README.md
baseimage: updated README.md
ruby-full: Ruby 2.2.0-rc1 released
debian: updated README.md
baseimage: updated README.md
Merge pull request #8 from minimum2scp/feature/ruby-2.2.0-rc1

ruby-full: Ruby 2.2.0-rc1 released
debian: updated README.md
baseimage: updated README.md
Merge branch 'master' into feature/remove-jemalloc-from-ruby-full

Conflicts:
	ruby-full/build/scripts/02-rbenv