clean-up code

fixes #91, #87
Fix failing tests
Add docblocks
Bug fix

If `DOWNLOAD_ENABLED` is not defined, return false
CS fixes
Fix explicit join bug
Conform query style to existing standards
Merge pull request #96 from texdc/160_clean_up_others_mess

clean-up work
#99 - Fixes the non-blocking modal problem
#99 - Fix missing help text
#99 - zc_install issues
Addresses:
- help text doesn't fire on db-upgrade screen
- hard-coded alert messages need to be split off for multilanguage support
#99 - zc_install issues
Addresses:
- if upgrading from 139 to 150 no profiles are assigned, so must set a default
#99 zc_install issues
- Removes obsoleted adminCandidate element
- Adds progress message
Fixes #101 Large sites and SaleMaker vs Specials
#99 zc_install issues - as upgrade stages are completed they aren't correctly updated on-screen
#99 - zc_install - allow upgrading from additional older versions
Fixes #101 Large sites and SaleMaker vs Specials
Remove debug code
Fixes #101 Large sites and SaleMaker vs Specials
Fix typos shipping on the brain
#99 - zc_install issues
Fixes #101 Large sites and SaleMaker vs Specials