Update authentication.texy
Update authentication.texy
Merge pull request #57 from mrtnzlml/doc-2.1

Fixed createComponentSignInForm method
Quickstart: Fixed typos.
Quickstart: Fixed links to another page in documentation (TOC).
Quickstart: English words translated to Czech.
Quickstart: Fixed code indentation in example and line number pointing to title block in layout template.
Quickstart: Added "namespace" and "use" to code examples with presenters definition.
Quickstart: Fixed sandbox tree structure according Nette 2.1.
Quickstart: Added warning about possible collision of SimpleAuthenticator and UserManager service and instruction how to solve it.
Quickstart: English version synchronized with latest changes in Czech version.
Quickstart: Fixed typos.