Check for Table and Column Before Changing

- Check for Table `CollectionVersionBlocksOutputCache` before `truncate`
call
- Check for Column `btCachedBlockRecord` before `set`

Correct error while upgrading to 5.6.1 as `btCachedBlockRecord` does not
exist
Merge pull request #987 from mkly/fix_installer_cache_flush

Check for Table and Column Before Changing