Update to 6.0.0a

* Switch to 6 branch
* Replace interpreters with REPLACE_*

Changelog:
Version 6.0.0a Dec 14th 2013

    Remove wrong warnings from logfile
    Fix LDAP authentication
    Fix LDAP configuration
    Fix Share dialog
    Fix migration under certain conditions
    Fix database encoding for old PHP versions
    Fix select all checkbox
    Fix migration with lucene search enabled
    Fix migration for postgresql

Version 6.0.0 Dec 11th 2013

    User Avatars
    Previews in files app and other places
    Updated design, less clutter and more whitespace
    Public gallery sharing
    Activities
    Better file conflict handling dialog
    Improved public App API
    Sharing API
    Example Files
    Share Email Notifications
    New Doctrine based database layer
    Plural translations
    Refactored OC.dialogs (both code and design wise)
    Priorize often used languages in personal-settings language selection
    Update jquery to 1.10.0 and add jquery-migrate 1.2.1
    Show a summary as the last filelist entry
    Improve app-management (more verbose error-messages)
    Show 窶弄ore apps窶� link to app administration directly in app navigation
    Templates for newly created files
    Add MB indicator to size column
    Google Drive external storage uses a new library
    New icons for shared and external folders
    File uploads conflicts dialog
    Possibility to prepopulate a new users home with a skeleton
    Public upload with encryption enabled
    Users now can decrypt the files again if their encryption app was enabled
    Many quota related fixes
    Total used space (with quota) now only counts user窶冱 own files
    Many external storage fixes, improved performance
    Improved file navigation performance by using Ajax calls (no full page reload for each folder)
    The file owner can now also restore deleted shared files
    New version drop-down with previews and the ability to downloading versions directly

(ryoon)