overwrite FileUtils#cd to return block result as same as Dir.chdir
revert ScmWorkspace#system_at_root! implementation of version 0.3.0
increment build version to fix FileUtils#cd to return the result of block if block given.
comment source code URL to see original source code
Merge pull request #4 from groovenauts/fix/fileutils_ch

fix FileUtils#cd to return the result of block if block given.