Update string.rst

These changes should be checked for accuracy, especially regarding tail(). 

The documentation for analogous methods in String should be modified in the same way.
Composer installation instructions updated for 2.5

Cake is installed to a different directly, contrary to the previous documentation.
Merge pull request #1381 from sydnerdrage/patch-1

Composer installation instructions updated for 2.5
Update security.rst
Merge pull request #1382 from hervethouzard/patch-2

Update security.rst
Removes the Repositories section

Repositories section is no longer needed in the sample composer.json file.
Updates CakePHP version number in sample composer

Updates the CakePHP version number in the sample composer to 2.5.0+
Merge pull request #1387 from jtyost2/patch-2

Removes the Repositories section
[fr] Follow #1387

Removes the Repositories section
[fr] Follow 3237ba0

Removed the Lib/ part for custom Route class path
[fr] Follow #1363

Corrected BaseLog path from Log to Log/Engine.
[fr] Follow #1359

Added example to find count for custom find type
[fr] Follow #1362

Adding a guide for permissions on temporary directories
Merge pull request #1380 from alanfgh/patch-24

Update string.rst
Change suffix to prefix in String tail docs
[fr] Follow #1380

Update string.rst
Update authentication.rst

I'm trying to add a link to the blog tutorial's auth section, since there is a bunch of setup work that needs to be done for auth to work, and it's not covered in the main documents (Book nor API) - Having a bit of trouble with the markup however - it's not rendering in github, but I think I've followed the convention - my changes here are on lines 14->21.  Jack Fruh, jack@fruh.net
Merge pull request #1391 from basementjack/patch-1

Update authentication.rst
Update formatting and use relative link.
Merge branch 'master' into 2.6