Update bootstrap.sh after QA
Update bootstrap.sh after QA

- Give more meaningful message if a repo does not exist
- Run make clip-rhel7-iso after bootstrap. There is no reason to prompt
  the user if they would like to continue.
- Check repo directory for proper permissions. Warn the user and exit
  before continuing.

ykhodorkovskiy/clip,rprevette/clip,ykhodorkovskiy/clip,rprevette/clip,ykhodorkovskiy/clip,rprevette/clip,ykhodorkovskiy/clip,rprevette/clip