TODO: fix dependencies in rake files
TODO: put in timeout when installing gems
TODO: check for network connection
TODO: perhaps look in installed rubygems cache first
TODO: make rubygems dependency fail immediately and gracefully?
      * in bin/sandbox?
TODO: replace backticks for gem installs with open4 library?
TODO: allow for sandbox to be rerun against existing sandbox to update it?
TODO: test against various OS platforms
      * BSD
      * OSX
      * Gentoo
      * Debian/Ubuntu
      * Could it work on Windows?
      * ?
TODO: test against other shells
      * csh
      * zsh
TODO: test against other ruby versions?
      * jruby
TODO: allow gem versions to be specified when installing
TODO: better documentation
      * of the codebase
      * in the readme
TODO: improve ui output
      * use verbosity level
      * include more messages about status
TODO: user config
      * set list of ruby variants to query?
      * list of gems to install
          ~/.sandbox/config
TODO: allow for install of ruby/rubygems
      * how
        * select dynamically?
        * preset in config file?
      * MRI, JRuby, Rubinius?
        * each would have their own install method
        * rubygems install would vary then
TODO: perhaps the following could be added to the activate script???
      # function not_sourced() {
      #   ## ZSH source check
      #   test -n "$ZSH_NAME" -a "$HISTCMD" = "0" && return 0
      #   ## BASH source check
      #   test "`basename $1 2>/dev/null`" = "activate_sandbox" && return 0
      #   ## script was not sourced
      #   return 1
      # }
      # function exit_with_warning() {
      #   echo "You must source this script (ie. source bin/activate_sandbox)"
      #   exit 1
      # }
      # not_sourced $0 && exit_with_warning
      # unset not_sourced
      # unset exit_with_warning
      
      # OTHER WAYS
      # ====
      # ONLY WORKS FOR BASH
      # if [[ "$BASH_SOURCE" == "$0" ]]
      # then
      #    echo "script was executed, not sourced"
      # fi
      # ====
      # COULD WORK FOR BASH:
      # if [ -n `readlink -f $0` ]; then
      #    echo "script was executed, not sourced"
      # fi