All Symfony requirements set to 2.6

* Avoiding some security issues
remove unused getExtensionName in favor of getAlias
Added final to all static-access classes
Issue #371

* Added enabled parameters in some extensions
Merge pull request #377 from xphere-forks/fix/extension

[Core] Remove `getExtensionName`
Merge pull request #379 from elcodi/hotfix/final-classes

Added final to all static-access classes
Merge pull request #381 from elcodi/hotfix/added-enabled-parameters-extensions

Issue #371
Merge pull request #376 from elcodi/feature/symfony-2-6-requirements

All Symfony requirements set to 2.6
State Transitional Machine for Elcodi.

This is an implementation of a State Transitional Machine and the intergration
with given Elcodi implementation.