[createiso] Use shell script for runroot (lsedlar)
    
    - Merge #357 `Improve error messages for gathering packages` (dennis)
    - [test] Only check bootability for images on x86_64 and i386 (lsedlar)
    - Improve error messages for gathering packages (lsedlar)
    - Merge #339 `Refactor failables, step 1` (dennis)
    - Refactor failables (lsedlar)
    - Stop setting release in OSBS phase (lsedlar)
    - Merge #351 `Remove ambiguous imports` (dennis)
    - [test] Correctly check bootable ISOs (lsedlar)
    - Remove ambiguous imports (lsedlar)
    - Merge #347 `Remove duplicate definition of find_old_composes.`
      (lubomir.sedlar)
    - Merge #342 `Simplify naming format placeholders` (dennis)
    - Merge #345 `createrepo: use separate logs for different pkg_type` (dennis)
    - Remove duplicate definition of find_old_composes... (rbean)
    - [createrepo] fix 'createrepo_deltas' option (qwan)
    - createrepo: use separate logs for different pkg_type (lsedlar)
    - Simplify naming format placeholders (lsedlar)
    - Treat variants without comps groups as having all of them (lsedlar)
    - Always generate rpms.json file (lsedlar)
    
    Signed-off-by: Dennis Gilmore <dennis@ausil.us>