use constants for url generator

available since symfony 2.3 which is also the requirement of silex master
small optimization
merged branch Tobion/patch-2 (PR #766)

This PR was merged into the master branch.

Discussion
----------

use constants for url generator

available since symfony 2.3 which is also the requirement of silex master

Commits
-------

f04f777 use constants for url generator
merged branch Tobion/patch-3 (PR #767)

This PR was merged into the master branch.

Discussion
----------

small optimization

Commits
-------

bf71922 small optimization
remove deprecated calls in Route
merged branch Tobion/patch-1 (PR #765)

This PR was squashed before being merged into the master branch (closes #765).

Discussion
----------

remove deprecated calls in Route

Commits
-------

ec615cf remove deprecated calls in Route