Hide concrete5 version number in upgrade page

If the constant APP_VERSION_DISPLAY_IN_HEADER is set to false,
unregistered visitors can still determine the currently installed
version by visiting the page /index.php/tools/required/upgrade.
Let's hide the version number when APP_VERSION_DISPLAY_IN_HEADER is
set to false.
Allow users to search for localized group

Groups are listed by their localized names. So, let's enable users to
perform searches by localized names...
allow addBlock to use a string as a handle
thanks aghouseh
Added tools URLs that are requested through "index.php" to the robots.txt.
added image input function
One of the missing input options is image. It is added here, and plays well with both fIDs and string paths
added miscFields to Hidden input element
to add classes for javascript functions, or html5 data-X information
Fixes the display ordering when a page is duplicated.
Fixed dialog not opening on consecutive page dropping.
Tell Zend to not parse messages.po files

Zend tries to load messages.po files at every call. Let's avoid this,
since the files to be loaded are called messages.mo, but usually
developers keep their uncompiled version in place.

Please note that since parsing messages.po fails, they are not cached, so
Zend tries to load them at every page call.
Ignore also hidden files/directories
remove unused installer code
make sure permission keys are imported just once
Don't show Download button for Multi-Site
Load all translations with changeLocale

Currently, Localization::changeLocale loads only the core translations:
packages and site translations have to be loaded manually.
It's better to load all translations when switching the current locale,
since all the localization files should be considered as a whole.
Add Message-ID header to sent emails

The Message-ID header should be present in sent emails.
If it's missing many spam detectors mark emails as spam.
Fix Dutch dateFormat

The Dutch dateFormat should be dd-mm-yy. At the moment a German dateFormat is defined.

See also:
- http://en.wikipedia.org/wiki/Date_and_time_notation_in_the_Netherlands
- https://code.google.com/p/jquery-ui/source/diff?spec=svn3982&r=3982&format=side&path=/trunk/ui/i18n/jquery.ui.datepicker-nl.js
Use Minor Version tracking for npm packages

semver should probably just be on the minor version not the patch
version so we track bug fixes
Merge pull request #1722 from worldskills/fix-update-multi-site

Don't show download button for Multi-Site
https://hackerone.com/reports/4939

and some indenting