Improve ajax call to build page url slug

* Disable form submission until ajax request has finished
* Don't do ajax request if page name is the same as the previous ajax
  request
* Take in account the ajax response (success of fail) only if it's for the
  last ajax request.
Fixed menu file paths, some of them were absolute.
Update core_scrapbook_display.php

Solve fatal error that *can* occur in automated job (Index Search Engine - All). Check if block (still) exists. 

Fatal error: Call to a member function getInstance() on a non-object in 8 core/controllers/blocks/core_scrapbook_display.php on line 32
Merge pull request #1363 from akodde/patch-2

Update core_scrapbook_display.php
Fix PH 5.4 error and Cleanup

Fix PH 5.4 error and Cleanup

- Pass `$controller` to form
- Add ccm-ui wrapper
- Remove closing `?>`
Fix backup messages

The correct way to signal errors in controllers is $this->error->add()
and not $this->set('error', array(...)).

Furthermore the redirect after a successful restoration should be
restoration_successful and not backup_successful
Fix missing/wrong translations
Fix to enable building with LESS 1.4

Since LESS 1.4.0 (~"@var") is removed.
We should use @{var}
Merge pull request #1386 from mlocati/fix-backup-error-messages

Fix backup messages
add jHandle support
Merge pull request #1388 from Remo/job-handle

add jHandle support
Merge pull request #1340 from mlocati/fix-slug-ajax-build

Improve ajax call to build page url slug
remove BASE_URL from getBlockTypeAssetsURL

avoid having http:// in these includes when a site runs with https://
Let's use Grunt instead of shell scripts

Available grunt tasks
* grunt css:debug
  Build CSS files from LESS files, without compression
* grunt css:release
  Build CSS files from LESS files, with compression
* grunt css
  same as "grunt css:release"
* grunt js:debug
  Build JavaScript files, SourceMap files and link them together
* grunt js:release
  Build only JavaScript files, without SourceMap files
* grunt js
  Same as "grunt js:release"
* grunt debug
  Same as "grunt js:debug css:debug"
* grunt release
  Same as "grunt js:release css:release"
* grunt
  Same as "grunt release"
Fix minor problem in README
Fix to enable building with LESS 1.4

See https://github.com/twbs/bootstrap/pull/6780
Made the field bigger for job responses so we can have really long responses (or errors)
Merge pull request #1394 from Mnkras/jobs-status-bigger

Made the field bigger for job responses so we can have really long respo...
State that build instructions are in build folder
Merge branch 'patch-1' of https://github.com/mlocati/concrete5 into grunt_merge