publish composer changes
Merge branch 'patch-21' of github.com:Remo/concrete5 into vet_composer_workflow_regression
Vet Composer Workflow PR and Button Text

- Vet composer worflow pull request
- Make Publish button display "Submit to Workflow" when under workflow
Change `require_once` to `Loader::library`

Change `require_once` to `Loader::libary('3rdparty/Zend/Cache')`

This allows for overrides when using with Zend
Merge pull request #981 from mkly/vet_composer_workflow_regression

Vet Composer Workflow
updating version
Merge pull request #982 from mkly/fix_zend_cache_loader_library

Change `require_once` to `Loader::library`
Fix `getStyleSheet` CSS File Retrieval

Fix `View::getStyleSheet()` css file retreival

`.css` files are not retrieved from getRecord so this always returns
blank

Change `Environment::getOverrides()` to cache all files not just files
that end in .php
adding flush to upgrade
Merge pull request #985 from mkly/fix_overrides_cache_css_js_getstylesheet

Fix `getStyleSheet` CSS File Retrieval
more bug fixes
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
tweaks to environment and view
Merge pull request #987 from mkly/fix_installer_cache_flush

Check for Table and Column Before Changing