Update image_prep.sh

Adding noninteractive flag for package installation
attempt to quieten rvm
Minor fixes

- remove installation of non-existent package
- don't install gem documentation
- use nokogiri-1.6.1 since nokogiri-1.6.2.rc1 since 1.6.2.1.rc1 doesn't
  install when you run via remote command
Merge pull request #1 from galstrom21/patch-1

Update image_prep.sh
Merge pull request #2 from mattt416/minor_changes

Minor fixes
Create .gemrc on all platforms
Merge pull request #3 from mattt416/minor_changes

Create .gemrc on all platforms
Use bundler as intended (which removes need to specify nokogiri version)
Merge pull request #4 from mattt416/minor_changes

Use bundler as intended (which removes need to specify nokogiri version)
Install bundler gem on Ubuntu
Merge pull request #5 from mattt416/minor_changes

Install bundler gem on Ubuntu
clone correct branch
clone correct branch for cookbook repos as well as parent
dont remove berksfile.lock
Enable lib functions to be used without gerrit
Add tempest support
generate nose html report