Added a clear() function to Model.php (2.4 branch)

1.) Changed Pull Request from master branch to 2.4 (Old Pull Request: https://github.com/cakephp/cakephp/pull/1323)

2.) Updated return value in comment
Fix content-type header in cached views. Fixes issue #2358
Set content-type to xml to replicate existing behaviour
Remove trailing space
Update Model.php

fixed comment spacing
Fix test
coding standards elseif
coding standards whitespace and single quote
more whitespace coding standard corrections
Merge pull request #1341 from dereuromark/master-coding-standards

Coding standards
incorrect tab to space - whitespace coding standards
Update version number to 2.3.6
Merge pull request #1342 from dereuromark/master-coding-standards

incorrect tab to space - whitespace coding standards
doc block
Minor optimization of CakeEmail::_wrap().
fix absolute url generation
Merge pull request #1343 from Phally/patch-1

Minor optimization of CakeEmail::_wrap().
Merge branch 'master' into 2.4

Conflicts:
	lib/Cake/VERSION.txt
Merge pull request #1344 from dereuromark/2.4-router-url

fix absolute url generation
Fixed unit-test locales